Unlimited Study LIVE 📚 | JEE/NEET Grade 11 & 12 Motivation + Strategy

Indexed: 2026-05-17

[00:00:02]No, this is not your lecture. This is this is others 12th standard lecture.

[00:00:09]Yeah, just to give my credentials and all those who don't know I'm Anoj. Okay.

[00:00:14]Okay. These are my credentials. This is to be modified. This is now 19. Rest of this written here. So we follow approach called PI approach. POI approach is basically physical, organic, inorganic all club together. Right? So idea is that whatever you're learning in physical chemistry should be interlin with organic and inorganic chemistry as well.

[00:00:36]So last class we have started off something. So I'll just have a quick review of 5 10 minutes and then we take it forward so that all of you are at the same page right and then practice and other things will happen.

[00:00:51]Shall is my screen visible?

[00:00:53]>> Yes sir.

[00:00:54]>> Okay. So in chemistry there are three parts right? Physical, organic and inorganic, right? I think you also joined a little late yesterday or you were on time.

[00:01:02]>> On time. Okay. For the whole duration you were there.

[00:01:04]>> Okay fine. So physical, organic and inorganic. Physic chemistry is where we do numerical questions. Organic is when we talk about carbon and other members like alcohol, ether, phenol, alihide, ketones and all. Inorganic is when we talk about let's say phosphate, nitrate, chlorate these kind of ions, right?

[00:01:20]Periodic table basically you must have heard of. So these are three different parts and all three are equally important. All three are very important.

[00:01:27]For example almost one/ird weightage for each where you say mole. Mole is what?

[00:01:32]Mole is collection of so mole concept is the first topic of physical chemistry.

[00:01:36]You can say basics of mole concept or basics of chemistry we can call it.

[00:01:40]Right? So the first topic if you say mole what is mole? Mole is collection of 6.02 into 10^23 entities. Right? So if you have these many numbers of electrons you can say one mole of electron. These many number of atoms you can say one mole of atoms why like you can write for any other quantity of chemistry but remember it is not to be applied something which is not in chemistry right so as we say dozen is 12 mole is this number and every time you can't write this number so every time you can't write this number hence you have to use this number very carefully we can write na or n in place of this number okay you can see the number na N A N or capital N that will also represent this number. Every time you will avoid writing this big number.

[00:02:28]Fine. So this is the definition of more.

[00:02:31]Fine. The next thing which we discussed was certain questions on this questions.

[00:02:36]I'll not take right now because this is already being done. So I'll discuss with Melinda and Shelly separately these questions and practice in detail. Okay.

[00:02:46]Because others have done that will waste your others time. We talked about a concept of amu.

[00:02:51]If you have a single atom, if you have a single atom like 6 C12, 6 C12, its mass is how much? 12 amu. Okay.

[00:03:03]Sh your classes currently will be 2 to 6 for physics and I think your group is created already. Is it is a group created for you? Sh's prep or something like that already.

[00:03:27]single atom 6 C12 this 12 is what this is called mass number and 12 am atomic mass unit will be the mass of it fine >> are you addressing the atomic number >> atomic number is first six is atomic number 12 is mass number. Okay. So just to give you an idea, see whenever you write any element, any element, there are two numbers zed and A. Zed is atomic number and A is atomic mass you can say or mass number.

[00:04:09]Okay.

[00:04:12]Fine. Now symbols are fixed. we can't change it. So let's say we write 6 C12.

[00:04:18]The six is value of zed and this 12 is value of A. Is that okay? And this Z will be equal to number of electrons.

[00:04:26]This will also be equal to number of protons. A minus Z will be equal to number of neutrons. Protons plus neutrons which is called nucleons is Z + A minus Z which is A. It is called nucleons.

[00:04:42]So how many of you know from 10 standard knowledge these things raise difficulty right shall is it clear?

[00:04:52]>> Yes sir.

[00:04:53]>> So quickly solve one question 238.

[00:05:00]Find out EPN.

[00:05:06]Okay. Find out EPN.

[00:05:09]Find out these values for 9238 quickly.

[00:05:15]Electron, protons, and neutrons.

[00:05:19]Other answer should be what? 92 92 and 146.

[00:05:35]Easy question.

[00:05:37]Now if I ask the same question for H2SO4 find out EPN what's the answer? Hydrogen is given as 1 H1 sulfur is 16 sulfur 32 oxygen is 806 try solve me is it clear now I'm asking for one molecule of H2O4 what will be answered so to solve this question there is a simple approach that you need to follow you please write it like this don't do verbally don't do in shortcuts there's a method for write H SO which are components of H2SO4 method.

[00:06:21]It looks like but it will save lot of time and it will also save you from mistakes and this method is to be used for any question.

[00:06:31]Okay. So let's say today you are finding an easy question you can think but tomorrow you can get a difficult question again this method will help you out. Shall is it clear? So first you write this kind of table HSO. What are HSO? These are elements of H2SO4.

[00:06:48]Now we write 1 H1 16 32 A to 16. What are these numbers? These numbers are Z and A values. Then what is Melinda? What is it's melinda right? M E MI. Okay.

[00:07:03]Meinda. So what is E for this case? NP and N 1 - 1 that is 0. Next case, 16 16 32 - 16 16 8 16 16 - 8 8 But remember you don't have just one hydrogen you have two hydrogen so multiply by two you have one sulfur multiplied by one you have four oxygen multiplied by four multiply because I'm not solving for HS I'm solving for H2SO4 Shal is it clear >> yes sir >> okay Shal and look alike So if sorry if I call you Di sometime so I have to set because you look like Dr. Okay. Yeah. So they are sisters. So Driti is with us in 12th standard. She has joined for 11th standard. Both were there with us. I think you joined for 9th right? Ninth >> 10th and now 11th. Yeah.

[00:08:01]>> So any difficulty in this part any issues?

[00:08:08]>> So what's the number if you multiply two? Can I say this number is two number circle 0 into 2 is not two it's zero only 16 16 final numbers and circle mistakes 32 32 32 STP speed test paper add numbers 50.

[00:08:42]Add the number. Add the number. How many of you understood this question? Raise your hand.

[00:08:59]or one molecule of H2SO4. Adita, is it clear? What if if you have two moles of H2SO4? Everybody?

[00:09:10]Sh can you answer it? If you have two moles for one molecule, this is my answer for two moles. What will be my answer?

[00:09:21]Two moles means 2 into Na number moles is a big number. What is that number?

[00:09:28]6.02 02 to 10^23 and what do we call this number? Na. So can I say two into na numbers are there? So what will be our answer? Can you answer Shelly Melinda?

[00:09:42]For one unit for one S2 answer is 50 50 48 for these many H2 what will be your answer?

[00:09:54]Exactly. Multiply 2 na in all the numbers. Shall is it clear?

[00:10:00]>> Yes sir.

[00:10:03]>> Yes sir. Two multiply note please note on this whole question.

[00:10:14]Any difficult in this part?

[00:10:24]All right.

[00:10:47]Any problem with this now?

[00:10:54]Have you heard of term molecular weight all of you? Molecular weight. What is molecular weight?

[00:11:07]>> Okay. So you can add the atomic weights of all the members of the given molecule. Right? That's a molecular weight, right? Okay. Adita, can you answer? What is molecular weight of HNO3?

[00:11:22]1 + >> no 14 >> plus 6 >> very good. How much it will come?

[00:11:34]>> 63 48 + 14 48 49 will say 63.

[00:11:41]So when you say 63 if you take one mole of HNO3 how much is the mass? 63 g.

[00:11:50]And if I take just one unit or one molecule of HNO3, what is the mass?

[00:11:57]63 U or 63 units or 63 basically amus you have added, right? Is that okay? Are you understanding this logic?

[00:12:06]Shall is that clear?

[00:12:08]>> Yes sir.

[00:12:09]>> Okay. So now Shal will answer this question. What is H2S04 molecular weight? Look at this data and tell me others please also try. What is its molecular weight? H2 is a four.

[00:12:25]Please try to answer H2SO4 molecular weight 98 g per mole. Good. Excellent. Others please be quick. Easy question. Add H2 multiply four 98 98 g per mole. Okay.

[00:12:53]>> Yes sir.

[00:12:53]>> 98 g per mole. That means if I take one mole it is 98 g. You took two moles. Two moles.

[00:13:01]Two moles is how much? 196 g.

[00:13:05]Now let's say tomorrow somebody gives you a question. 196 g of H2O4 electrons, protons or neutrons.

[00:13:13]196 g divide by 98 g per mole we get two moles 2 moles is 2 NA 2 NA each sol multiply. So if I ask a question two moles H2O 4 how many electron proton neutron? This is my answer. If I ask a question 198 196 g of H2O 4 how many electron proton neutron? Again this is my answer. Are you understanding this?

[00:13:35]Please note K.

[00:13:37]Kindly note it down and I hope it should be very much clear.

[00:13:47]Clear conceptually I'm g at concepts question Han, this will be moles.

[00:14:57]Yes, we'll listen.

[00:15:02]We'll discuss. We'll discuss.

[00:15:06]Good that you started trying. Very good.

[00:15:27]Now I'll just quickly review the concept of gram atom gram molecule and then we proceed further right because practice let's start this is it done Okay.

[00:15:45]So, gram atom, gram molecule, gram ion.

[00:16:03]You can take tea, coffee, Black coffee, >> black coffee also. You can give boost.

[00:16:17]Black coffee, tea, horics, anything you can take. Badam milk also. Yes.

[00:16:30]Normal coffee with sugar with sugar. proper coffee lot of energy is exhausted so we'll take sugar shall we start chuk so you please pay attention not to coffee to the discussion so when it is gram atom gram molecule or gram ions whenever you see these terms you have to cut it and write in place of this moles whenever you see these terms you have to just cut it and write moles because these moles. Okay. But there's a special thing. This word gram atom can be used only for atoms. This word can be used for molecule. And the third word can be used for ions. And the last word can be used for atom, molecule or ion. Shall is it clear?

[00:17:23]So if we want to find the difference between atom, molecule and ion. Can we say atoms representation is let's say somebody write C H O N SP what are these atoms if you say CO2 NO2 N2 H2O these are what molecules if you put charges CO3 minus2 NO3 minus H3O plus P4 minus3 then what is it these are ions can you differentiate these three things so if you make a statement that 10 g atoms of P4 minus3. 10 g atoms of P4 minus3. Is it a right statement or wrong statement?

[00:18:06]Is P4 minus 3 an atom? So, is it a right or wrong? Wrong. Is it clear? Can you say 10 g atom of carbon? Yes, because carbon is an atom. Can we say 10 g atom of carbon dioxide? Is it a right statement? Wrong statement. Wrong.

[00:18:21]Because CO2 is a molecule.

[00:18:24]Sh. Is it clear? Can we say 10 g moles of carbon dioxide shall 10 g moles of carbon dioxide can we say?

[00:18:34]>> Yes sir.

[00:18:35]>> Gram moles can be used for all the three. Right.

[00:18:40]Now can we say 10 g moles of NO3 minus?

[00:18:43]Yes. Can we say 10 g moles of carbon at that's also correct. Okay. So it can be used for any of them. So gram moles can be used for any of the cases. Hence gram moles is like a universal unit. But there's a problem. If you say gram moles and you say 10 g moles of nitrogen, then there's a confusion whether it is N or N2. We have to give clarification whether it is N or N2. If it is N, it should be 10 g atoms of nitrogen. If it is N2, it should be 10 g molecule of nitrogen. But if you say 10 g moles of nitrogen, that means it can be N or N2 both. So you have to give clarification.

[00:19:17]Is that okay? To make it more logical, more clear. So please note down this part quickly.

[00:19:25]It's a portion.

[00:19:31]Thank you.

[00:19:49]Any issues with this? Any problem with this part?

[00:20:02]I've written a statement here. X g moles of nitrogen is an ambiguous statement.

[00:20:07]You understand ambiguous means it has multiple meanings, right? So not clear statement because whether it is N, nitrogen can be N, N can be N2 and you're using gram moles. So it's a confusion.

[00:20:22]So the confusion will go if you say X g moles of nitrogen atom then it is N. If you say X g moles of nitrogen molecule that's also clear that means we talking about N2. If you write this you talk about N2. If you write this you talk about N. Make sense? Any problem with this? Any issues with this part?

[00:20:46]Okay Charlie. Is that clear?

[00:20:52]>> Yes sir.

[00:20:54]>> Okay. Great. So now we'll move forward.

[00:20:56]Yes. Adita.

[00:20:57]>> So sodium sodium.

[00:21:02]>> Yeah. Extra moles of sodium you can say because that will not be molecule that will be taken as atom. Good.

[00:21:09]All right. So now let's see certain things further in this regard.

[00:21:17]Let's try this question on your screen.

[00:21:21]coming now.

[00:21:23]Try take your time and try to answer.

[00:21:46]Yes. Atomic weight is 7532.

[00:22:13]Which one?

[00:22:16]Check carefully. What is the question?

[00:22:45]Which one?

[00:23:42]See the question is element A atomic weight 75 B atomic weight is 32 combined to form a compound X and 3 mole of B combined with 2 mole of A. So basically it is can I say A2 B3?

[00:24:09]Yes or no? 3 moles of B combined with two moles of A2 to B3 A to B3 molecular weight it will be 2 * atomic weight of A which is 75 plus 3 * atomic weight of B which is 32 so if you solve this number this is 150 + 96 which will come 246 g per mole but this is not the answer because the question is for >> five moles of X so you can miss this part five moles of X what will be number this into this for one mole for five mole it is five times more so what's my answer >> option B >> yes 1 230 g or 1.23 23 kgs answer.

[00:24:55]Is it clear now?

[00:24:57]>> Very good.

[00:25:00]Question.

[00:25:10]So see all of you have now moved from 10th to 11th. Right? Now there will be many changes and you can say this is the bad part of our education system, good part of education system but a lot of changes you will observe. Okay. One big change is the way you were learning till 10th and the way you will learn now in 11th it is completely different. Okay.

[00:25:32]So physics right towards the exam you can study and get the score. Now you can't do that because the syllabus is huge. So syllabus is almost if you compare with 10 standard the volume of 11 standard is at least 5x if not less at least 5x I'm telling putting PCM together versus PCM in 10th standard so 5x volume difference then you all are preparing for certain examination or let's say you want to prepare for clarifying your concepts so you have to go deeper also right be JWE ne concept clarity so you will do variety of questions So your practice hours should be more.

[00:26:18]It's not just theory, it's theory plus application. So both will be required.

[00:26:22]Hence it is requested to all of you that you please pay more and more effort from day one. And these extra five seven days will make huge difference. See the students like you who have joined now and students who will join let's say from April 1 or April 15 also batch will start even batch will start in May also there will be a huge difference. We have observed every year. What happens when you start early you at least you have chance to accumulate with the whole flow even if you waste half a month after 15 days you are through you'll get a rhythm of the whole thing but if you join late late then process day one say open and we have to understand each and every concept in class okay and it's my assurance that all my students till date those who are serious students Those who have put good hard work beat any examination IIIT NE even for board examination also they've been toppers only right so I'm taking name of Kevin Martin rank two all India rank two I have taught similarly rank 8 hik then 27 nickel huda so many students are there right not one or two so the idea is very simple if you just follow what teachers are telling in classes and you work upon your problem areas don't procrastinate That's a good that is what is needed till the end.

[00:27:50]Right.

[00:27:54]Right. So we have to be always on our toes and we have to always keep working for next two years and continuation.

[00:28:00]Okay. Whatever is your target it will be fulfilled. Right.

[00:28:04]Those questions clear. Can I go to the next? Let's try out the next question on your screen. Which of the following samples contain the largest number of atoms? Now, what I have given you is moles. And what I'm asking is atoms.

[00:28:20]I've given you moles. Moles. Moles.

[00:28:22]Moles. And I'm asking atoms.

[00:28:24]What is moles?

[00:28:27]Whenever you're given moles, it's a collection of how many things?

[00:28:30]>> Na things. Yes. So the this is a molecule.

[00:28:35]CH4 is a molecule and 2.5 moles are there. So can we say it is 2.5 into Na units of CH4 2.5 into NA number it's up to you. You want to write 6.0 to 10^ 23 that's also okay but I prefer writing this because that saves time. So I'll write 2.5 into Na and then CH4 has one carbon and four hydrogen. So 1 + hydrogen number of atoms.

[00:29:10]This is number of molecules. Each molecule has one carbon and four hydrogen. Please complete it. Try to answer and try to do for other cases also.

[00:29:23]Clear.

[00:29:25]Shamr G clear. Good. Shall is it clear?

[00:29:28]Yes sir.

[00:29:30]>> So can you do it for all the cases and give me the answer? Remember physical chemistry is all about efficiency and speed.

[00:29:40]Okay. So don't do that.

[00:29:58]Good answer is D. Correct answer.

[00:30:01]Second question.

[00:30:03]10 NA H just one unit one. 4 NA sulfur 1 oxygen 2 1.8 NA sulfur 8 3 NA nitrogen 1 hydrogen 3 solve please 12 NA 14.4 4 NA I 12 NA you up already 10 NA and this is 2.5 N this is 12.5 so which is the maximum number doable question is it clear >> yes sir Melinda is it Shasha done samriti. Very good. Take your time. Take your time. See again we are not in no hurry. We are starting early. We will have sufficient time to complete our portions right in proper way.

[00:31:40]You come in morning. Tomorrow we'll discuss your doubts.

[00:31:50]Any issues in this? Okay. Now see the next try.

[00:32:09]Try this.

[00:32:18]He can be a role model.

[00:32:21]He's preparing for JD Vas. He has got 98.7 98 9 sorry 99.7 99.7 percentile in mains first attempt and uh definitely within thousand rank for this year ID can I say that definitely good respectively respectively Bring bring that focus like focus J is an easy exam. It's not a difficult exam but you should be focused. Same goes with need. Need is even much more easier. And remember subject chemistry is the key. If you want to succeed in these exams, chemistry is the key.

[00:33:22]Easiest most scoring. And if you set rhythm with the subject, you can do full score. You get full scoring means advance also 80 85% score is possible.

[00:33:34]What's the answer?

[00:33:36]>> Yeah. Why atoms? This answer is given in bracket. So atomic weight of two elements A and B are 20 and 40. X g of A contain Y atoms. How many atoms are present in 12 g of B is the question. So now C atomic weight is what? Atomic weight is basically this is gram per mole and this is what gram per mole. You know the unit also or we can say amu.

[00:34:04]X g of A contains Y atom. So, a and b weight is x g atoms y. So, x g weight x gide atomic weight.

[00:34:22]How much is atomic weight? 20 units divide moles. Okay. Moles na multip moles into n is what? molecules but this time we talking about elements so basically these are atoms how much is this number sr why as per the question contains y atoms x g of a contains y atoms right so moles into na is y as per the question and what is the second part how many atoms are present in 2x g of b a 2x ga so you'll write 2x what is atomic weight of this >> 40 shall is it clear Yes sir.

[00:35:05]>> into na y into n is y. What is 2x 14 into n? Why?

[00:35:15]Why it is 2 y two cancel?

[00:35:20]So answer is what? Answer is y only you won't share.

[00:35:32]Any difficulty in this? Any issues with this?

[00:35:41]Please note down.

[00:35:46]So language of question is very clear.

[00:35:48]What are we doing in this question?

[00:35:51]X g 2 g x by 20 into n 2x 14 into n. Can I go to the next question?

[00:36:00]Question. There's no hurry.

[00:36:03]You take your time. This topic everybody takes their own time. Trust me. There will be students in 12th standard who are still struggling in this topic. But because this topic is complicated and since you guys move from 10th standards because that's why we are practicing a lot right. So a please answer this question.

[00:36:32]Calculate the number of O atoms and its weight in 50 g of calcium carbonate.

[00:36:41]Melinda, what is calcium's atomic number and mass number?

[00:36:48]20 and 40.

[00:36:51]carbon, oxygen.

[00:36:58]Use it and solve it.

[00:37:56]You can also solve this question.

[00:38:00]Meanwhile, this is an 11th standard. You can handle answer.

[00:38:20]11 friend.

[00:38:26]So there's no age of learning.

[00:38:31]What is molecular weight of calcium carbonate? Use this data and tell me 40 12 and 16. So how much?

[00:38:42]100 g per mole.

[00:38:46]And we have 50 given here. So how many moles will be there?

[00:38:51]50 divided by 100. See remember no need to mug up the formula. You say gram upon gram per mole will give you what unit?

[00:38:57]This will cancel out. It will become what? Moles.

[00:39:00]How many moles it will be? Half moles.

[00:39:04]Half mole. Calculate the number of oxygen atom in its weight in 50 g of calcium carbonate. Say half mole of this. Half mole means how many molecules? Can we say half into >> Na molecules of Ca3?

[00:39:22]Na is our graduous number.

[00:39:26]>> Yes. 3x2 Na atoms. 3x2 Na atoms. Right.

[00:39:30]So how many calcium atoms will be there?

[00:39:33]1x2 NA. 1x2 NA molecules. Each molecule has one calcium. one carbon and three oxygen. So what's the final answer? We can say half Na into 1/ half Na into 1. Half Na into three. This is calcium. If they ask if this is carbon and this is oxygen note easy what is weight of this in calcium carbonate how many moles of oxygen you have 3x2 moles how much is the mass van 3x2 moles what is the mass? 1 mole how much is the mass? 16 3x2 is how much mass?

[00:40:38]24 g. So oxygen mass is how much? 24 gass.

[00:40:43]Carbon is how many moles? Millinda half mole. Half mole. Half NH. Half mole is how many grams?

[00:40:52]Six. Calcium is how many grams? Half mole. Half into 40? 20. 20 + 6 26 + 24 is how much? 50.

[00:41:04]So in case you do mistake, you can always check. Total mass should not change. Calcium carbonate 50. Oxygen 24.

[00:41:13]carbon 50 g a that's wrong right how is it possible summation of mass of all the atoms put together should be equal to molecules mass isn't it that has to be the case right is it clear any problem in this part any issues in this conceptually sound question can you solve such question please note question you know the history of question like how question is formed and how it travels down so mostly all good questions emanate from international Olympiads okay or foreign author books few questions ped then further MC question right so if they want to give difficult question they can even ask in board exams nowadays these days raise difficult questions right so mostly you'll find they will take from somewhere so if your conceptual levels are high you'll feel it easy my approach is simple we will do difficult things here so that everything becomes Easy not vice versa.

[00:42:45]That will not solve the purpose. Again till 10th standard we solve good number of questions. In 11th and 12th youth you have to solve quality problems. Even you solve five good problems but that should clarify the whole concept is enough rather than running behind more and more questions. Right? And same type of question last question.

[00:43:06]Calculate the number of oxyen sodium sulfate this much. Then a question calculate the number of oxyen atom in 18 grams of water. Then question purpose because the concept is clear. Now I'll go to some different direction. Okay. So you you see the perspective from different ways you see the question and different variety of question. So that will decide how good you are in concepts. Please answer this question.

[00:43:29]Puran question simple question. Try to answer you've done.

[00:43:37]Okay.

[00:43:46]See basically the question is 14 total number of neutrons total mass of neutrons Charie up to this any difficulty?

[00:44:22]>> No sir.

[00:44:23]>> And please be like feel free to ask any question. Right.

[00:44:27]>> Okay sir. So in case you find any difficulty, yes 6C14 is an isotope of 6C12 7 mg. Mg is what? Millig.

[00:44:47]Both the questions are for this amount.

[00:45:37]Very good.

[00:45:42]Fine.

[00:45:44]What is mass given here? 7 mg of 6 C volume. Is it okay?

[00:45:50]So can we write W which is mass is 7 mg.

[00:45:55]Can I write 10 - 3 g? All of you agree?

[00:45:59]>> Yes. So we can write W is 7 into 10 - 3 g of whose weight is this? 6 C14 614 come Shre 6 C14 how many neutrons are there in one unit?

[00:46:14]Very good. 14 - 6 is 8. Shall is it clear?

[00:46:20]>> Yes.

[00:46:20]>> In single unit of 6014 we have these many neutrons. In single unit we have these many neutrons. Okay. How many units do we have? You have W is a weight.

[00:46:32]14 g per mole. 14 g per mole is the value for this. So you can say atomic weight is how much? This is atom, right?

[00:46:42]Carbon is an atom. So I'll not say molecular weight. That doesn't make sense, right? So you see atomic weight is how much? 14 g per mole. Please divide this. G cancel. Okay. You get moles. How many moles are coming up? It will be half into 10us 3. Any problem in this half into 10us 3 moles?

[00:47:05]>> Yeah that's okay. 5 into 10 - 4 you can write. Okay - 4 because half is what.5 minus one.

[00:47:19]Now this is number of modes. Is it clear me? Is it clear? Is it clear? These are what? Moles of whose whose moles are these? Carbons. What? What are we interested in? Number of neutrons and total mass of neutrons. And they've written assume that the mass of a neutron is mass of hydrogen atom. What is mass of hydrogen atom 1 H1 shelling?

[00:47:44]Can I say 1 amu?

[00:47:46]>> Yes.

[00:47:47]>> Okay.

[00:47:48]And amu for one atom, one mole atom, what is the value? We can say 1 g per mole. So what is the connection between mole and amu?

[00:47:58]So mole is basically what na * amu.

[00:48:03]Yeah. G* amu. Is that okay? That connection is clear. Okay. Gram is a bigger unit. How many times? A mu* amu into any * unit. Right? So just come to this question. Number of neutrons in this in one unit how many neutrons are there? So we can write in in 1 6 C14 we have neutrons equal to 8.

[00:48:27]So in half into 10^ -3 into na because remember this is moles this is moles into na to numbers how many units will be there 8 * half into 10^ -3 into na which is how much 04 na answer sheet copy.

[00:49:10]Yeah, it was subjective any difficulty in any way.

[00:49:21]Any problem with this part? Any issues with this part? Now total mass of neutron in this.

[00:49:31]What is mass of one neutron? One hydrogen atom which is 1 amu. How many neutrons do we have? 04 NA. So what's the answer? 0.4 NA amu.

[00:49:50]Fine value.

[00:49:54]N amu can I call this as 1 g so what's my answer 0004 g this is from your sheet question number check go to next page question number four on page number three answers Okay. Solve your question. Any problem with this?

[00:50:30]Is it clear?

[00:50:44]>> Neutrons and protons. Why should we take protons in this?

[00:51:08]So you're ignoring the mass of electron.

[00:51:09]That's okay. I understand what you're trying to say.

[00:51:13]Yeah, you can ignore that, right?

[00:51:21]Can you solve such questions?

[00:51:24]Can you go to the next? Please try this question. So first you write this percent by weight questions. Percent by weight is defined as amount of substance in 100 g of mixture. So very simple definition. Let's say I ask a question.

[00:51:42]There is a 70 g of mixture.

[00:51:48]of NaCCl and KCL and NaCCl is 30% by weight. What is meaning of the statement that out of 100 gram it is 30 g. So can you tell me the exact number of NCL and KCL in this mixture?

[00:52:07]What we a question of percentage only right answer Melinda 70 g 30% 70 g 70%.

[00:52:18]Is that okay? How much will be the value?

[00:52:23]21 g very good. And the other one >> 40 >> 49 >> 49 g good. This will be how much? 70 30% is 21 g and this will be 49 g. Shall is it clear? It's a direct question.

[00:52:39]>> Yes sir.

[00:52:40]>> Percent question.

[00:52:44]So percentage means what? 100 g how much? That is called percentage. Okay.

[00:52:51]Is that okay?

[00:52:54]Definition. If you have written this down, write down the definition.

[00:53:05]Mole fraction. What is mole fraction?

[00:53:09]Mole fraction as your name suggest moles of substance in one mole of mixture.

[00:53:14]Moles of substance in one mole of mixture is known as mole fraction.

[00:53:20]Okay.

[00:53:21]So one mole fraction.

[00:53:36]question.

[00:53:38]Let's say for instance you have A B and C and you have two five and three moles of A, B and C together in one vessel.

[00:53:58]So can you tell me how many total moles do we have? Sh. Huh? Very good. Up 10. A two. So what is fraction of A? What is mole fraction of A?

[00:54:12]2 by 10. A.

[00:54:15]What is mole fraction of B? It's very simple, right? But these simple things will be required for 12 standard also.

[00:54:21]When you do solution collative, mole fraction will again come. When you do chemical equilibrium, it will again come. So you should know these concepts from fundamental. So 5 by 10 and mole fraction of C is how much?

[00:54:33]Very good. Now do one thing. Add all the mole fraction and see what will come. 2x 10 + 5x 10 + 3x 10 is how much? Can I say 10 by 10 which is 1. So can we say summation of all the mole fraction is equal to one. Please note down.

[00:54:48]Sum of all the mole fraction is equal to one. Sum of all the percentages equal to 100.

[00:54:56]100 percentage measure to summation of all the percentages is 100. Summation of all the mole fraction is one. Make sense?

[00:55:07]Good.

[00:55:22]So initial 10 15 days it will take for all of you to settle down in 11th standard wibes I'll use this word because 11 standard wives are different from 10th standard completely different so faster you settle down easier it will be okay so practicing solving questions reducing wastage of time decreasing screen time these are the challenges right you have to handle okay reducing times where you gossip with friends, maximizing your overall study time, right? All these things you have to do.

[00:55:56]Sleep cycle control 10:30 maximum you sleep. Okay? And morning 5:30 wake up. 7 hours sleep is sufficient. Don't sleep more, don't sleep less. Make a proper routine. Be more disciplined. Okay? Me be more organized. These things will help you. Why I'm saying bio conditioning of this these things are required because that will help you in exam also. So once you are doing these things properly you will automatically will be better than half of the students who are like randomly doing things they don't have any idea about what to do how to do and all. So be more organized.

[00:56:31]When you make notebooks, make physics separate, chemistry separate, math separate. When you write notes, it should be legible at least by you, right? You can read your notes. It should not be like decode those notes, right? So, so be very what do you call more organized in simple words, right?

[00:56:54]fraction.

[00:56:56]So now we will solve certain other things but let me first take some questions please.

[00:57:25]Okay, we'll do from your hand out which is given to you. Please take out hand out all of you.

[00:57:39]All of you have this or come to page numbers.

[00:57:53]Copy.

[00:57:59]Everyone please try question number 54 on page number five. I'm writing here which all questions you're supposed to solve even I'll just get it here. No this module itself.

[00:58:18]>> Yes. N2P is neutrons to protons.

[00:58:55]Sh can see here also. You can see in your group also.

[00:59:03]>> Page number five. Question number 54 and 56.

[00:59:22]nitrogen 7 and 14. So atomic weight is 14. Nitrogen is 7 and 14. Okay.

[00:59:53]Can you show me?

[01:00:23]26 F56 26 F 56 6 C12 7 N14 protein one H1.

[01:00:42]Anything else?

[01:01:38]What is the answer for this question?

[01:01:39]NH4 plus >> 7 is to >> 11. Sub sh What's your answer?

[01:01:46]>> Option A.

[01:01:47]>> Option A 7 is to 11. So neutrons or hydrogen zero because H1 and protons into electrons charge.

[01:02:03]So answer very good 56. What's the answer?

[01:02:10]>> 7 is to 3. Okay. 56 is weight ratio of Fe to carbon. How many moles of Fe are there? Fe2. Then one more fee. Shelley, what's your answer?

[01:02:22]>> Uh 7 by3.

[01:02:24]>> 7 by3 answer.

[01:02:27]>> Okay. How many fees are there? Can you write? Fe2 and then a bracket is there and then they're writing Fe C N 6. So how many FE are there total? Two here, one here. Can I say three FES? Yes or no? Count carbon, please. Six carbon.

[01:02:44]Okay. Six carbon, six nitrogen.

[01:02:47]Yes or no?

[01:02:48]>> Yes.

[01:02:49]>> Okay. So, carbon is how many moles? Six moles. This is molar ratio. This value is molar ratio. What is the question?

[01:02:57]Weight ratio. So, you have to multiply this with what is iron's atomic mass? 56 moles into atomic weight. Is it clear?

[01:03:09]And what should I multiply here? SRI.

[01:03:14]Very good. So if you simplify this calculation this will be four and then this is how much? 14. So answer 7 upon 3.

[01:03:25]Easy.

[01:03:27]Can we answer such questions with much more comfort now? Great. Now see some more questions.

[01:03:43]57 1.8 8 ml of water >> 57 a in this 57 how many moles of electron are there in 1 kilog bunch of electron 1 kilogram bunch 1,000 g and electron mask >> 9.1 10 - 31 g kgs 31 kgs so we'll write that number and then divide it and then divide by na okay we'll do that don't worry come to this question I'm showing it now on your screen these two Five.

[01:04:16]This is based on today's learning.

[01:04:18]Today's learning basically mole fractions learning.

[01:04:22]Solve question number 32 and 33.

[01:04:30]Is it legible? Can you read it? Okay.

[01:04:37]Page number. This is page number.

[01:04:40]Shelly. You can refer to my sheet page number from class.

[01:05:50]I said that way.

[01:06:29]Get all 32.

[01:07:44]Question for 32. How many got the answer? Any answers?

[01:07:48]>> Sir, option B.

[01:07:50]>> 3x 8. Okay. What's your answer, Shelly?

[01:07:53]>> 1 by 12.

[01:07:55]>> 1 by 12. Okay. Take the question. A and B has 1/3 mole fraction of A. What is meaning of the statement?

[01:08:03]Meaning of this statement is in A and B what is mole fraction of A 1/3. So what is mole fraction of B? 23 23.

[01:08:17]Okay.

[01:08:19]And another mixture of B and C has 1/4 mole fraction of B. So if this is 1/4, what is mole fraction of C? 3/4.

[01:08:31]And both the mixtures are mixed in equimar ratio. What is equar ratio? Same number of moles. You're mixing same number of moles of each. Okay. Same number of moles of mix.

[01:08:50]Is it okay? So if you mix both of them, can you tell me what is total number of moles of C that you're going to get? C A B. This is B and C. These are mole fractions. Let's say I'd say moles are A and A for both of them. A and A. So how many moles of C are there? Actually 3 A upon 4 3x 4 A. Okay. Had it been 1 then 3x4.

[01:09:14]But if total moles are a 3x 4 A. Is that okay? And what are total number of moles? 3x 4 a divided by a plus a is total number of moles which is how much?

[01:09:25]So what's the answer?

[01:09:28]3x 8.

[01:09:30]Good simple question.

[01:09:33]What is mole fraction of let's say you are solving A? What's the answer? Fraction of A but in the same question what is mole fraction of A?

[01:09:48]C is 3x 8. What is A?

[01:09:53]So A is how much? 1 by 3 A into upon 2 A. Is that okay? A by 3 upon 2 is what?

[01:09:59]1x 6. How much is B?

[01:10:03]So B is you can say 2x3 and then 1x 4.

[01:10:08]2x 3 + 1 by 4 divided by 2 number. Can you solve 12? This is what 8 + 3 11 by uh 12 24 11 by 24. Now see 3x 8 can I write it as 9 by 24 if you don't mind 1x 6 can I write 4x 24 in add 9x 24 4x 24 and 11 x 24 what will become 24x 24 so when you mix two mixtures the final mixture will have summation of mole fraction again one is the logic clear how many of you understood this question raise your hand a is Clear B is clear. C is clear. Shall after mixing both of them. ABC mole fractions all he can solve and summation of ABC mole fraction will again come back to one.

[01:11:04]Are they clear? Can we try this question? Question number 33. Please the mole fraction of N2 in mixture of N and N2 and N is 13. Last question is clear.

[01:11:18]Anyone would like to write anything?

[01:11:20]Please not courage.

[01:14:12]any answer for this This is the question right?

[01:15:01]Okay. So, mole fraction of N2O in mixture of N2 and NO is how much?

[01:15:09]N2O and N O N2 and N O is 1/3 to you.

[01:15:19]Very good. This is one box.

[01:15:23]The mole fraction of NO in a mixture of N and N O2 is how much?

[01:15:28]>> Yes. So let me NO is how much?

[01:15:31]This is 3x4. So what will be NO2?

[01:15:34]1x4. Now you're mixing both of them in the molar ratio of 3 is to 4. Sh tell me if I assume 3A moles of this, how many moles of this I'm using? Very good. Now can you please tell me if you're using total 3 moles of it and this is 1/3 how many actual moles are there for it 1/3 of 3 a moles of this compound 23 of 3 a 2 a moles 2 a plus a 3 a break this is 4 a how much is this n is how much 3/4 so n am 3 a And it's a total amount 4 a match.

[01:16:22]Any problem with this? Any doubts with this?

[01:16:27]Any confusions?

[01:16:30]Is it clear?

[01:16:35]See this is individually is clear. Now these are mixed with the molar ratio of 3 is to 4. That means 3 moles of this with 4 moles of this. If you have total moles 3, what is mole fraction definition? Mole fraction of N2O which is 1/3 is moles of N2O. Shall is it clear? Divide by total.

[01:16:55]>> Yes sir.

[01:16:56]>> Moles of N2 N2 total moles 3 a value 3 a into 1/3 which is how much? A 3 a 1/3 is N2. What is 3 A 1/3? A 3 A 2/3 is what? This number. Similarly, 4 A 3/4 is 3 A and 4 A 1/4 is A. Now, as per the question, we have to find the after mixing both of them, I have a 7A moles mixture because 3 A is 4 A is total I have how many moles? 7 A moles. In 7 A moles, they're asking mole fraction of NO2. Where is NO2? Where is NO2? Just this much is NO2. How much is NO2?

[01:17:40]A. So what's my answer that is N2 N2 NO2.

[01:17:55]If a question comes what is mole fraction of see mole fraction of NO2 is how much? 1 by 7. Let's try mole fraction of N. How much is that?

[01:18:07]N is how much?

[01:18:11]3 A 3 A 2 A 5 A 5 by 7 a mole fraction of N2 solve 1 by 7 check N2 is how much a by 7 if you add all of them it will be one okay now all of you please take a break of 5 minutes and then we'll give you a small test to write see how much you I'm not testing your abilities. I'm just giving it just to understand how much you have understood in last one and a half hour or those who attended yesterday also. Okay. Rupes print out front back dur soft copy to you. You can solve from that. Okay.

[01:18:59]>> But be online. Don't go anywhere.

[01:19:01]>> Okay.

[01:22:25]Shelly, can you hear me?

[01:22:28]>> Yes, sir.

[01:22:29]>> Did you get the paper?

[01:22:30]>> Yes, sir.

[01:22:31]>> So, you can start solving now and we'll connect in the next class, right? You'll get the information further. I'm just ending this meeting.

[01:22:37]>> Okay, sir.

[01:22:38]>> Okay.

[01:26:52]Can you hear me?

[01:26:56]>> Yes.

[01:26:57]>> Please keep camera on.

[01:27:23]or is back or not.

[01:27:32]11th Shelly, please turn camera on.

[01:27:48]>> Yes sir.

[01:27:54]Blur blur blur.

[01:28:12]Uh now it is better clean.

[01:28:21]Yeah.

[01:28:24]Okay.

[01:28:27]We'll start in 2 minutes. Meanwhile, I can revise quickly what all you have done in the last class.

[01:28:34]Yeah.

[01:29:28]This last question is clear.

[01:29:30]Energy of an excited electronization energy of the Is this clear?

[01:29:47]This question is clear.

[01:29:50]Last last question there also.

[01:30:05]Full test.

[01:30:19]Ha. Please turn camera on. So look at this question. All of you look at this question.

[01:30:27]Thank you.

[01:30:30]>> So last question, right? What was he working? Just revising it. So it is.85 nanometer.

[01:30:40]So you said 85 into 10 raised ^ -9 m equ=.529 into 10 power - 10 into n² by z.

[01:30:58]So solve value anyone.

[01:31:05]How much was N coming up?

[01:31:10]Four.

[01:31:12]Okay. N4 velocity velocity is Z / N 2.188 into 10^ 6 m/s.

[01:31:27]So 1 / 4 into 2.188 into 10^ 6 m/s.

[01:31:37]Okay. Solve answer.

[01:31:41]Any problems with this? Any issues anyone with this question? This is the last thing we did and then we solve certain questions from DBPS and all.

[01:31:49]Right. That was the other discussion but classp.

[01:31:56]Now coming to the next question.

[01:31:59]Can I remove this? All of you have done this part. The next question is energy of an excited hydrogen atom is minus 3.4. Calculate the angular momentum of the electron in the given orbit.

[01:32:11]Okay.usus 3.4 energy. We have to check that. So see Yeah, if you start for n= 1, n= 1, what is the value of energy? It is -3.6.

[01:32:27]n= 2, what is the value?

[01:32:30]-3.4.

[01:32:32]N= 3, what is the value?

[01:32:34]>> -3.6 / 9. N= 4. What is the value?

[01:32:42]-3.6id 16. Please solve values.

[01:32:47]Note -3.6 is the value of EV at n= 1. As you go to n= 2, the value becomes -3.4. Why it is - 3.4? Because -3.6 / 2² - 13.6 upon 4 value 3.4.

[01:33:17]1.5 approximate right 1.51 to be more precise. Next one.

[01:33:30]>> 0.85. Note all these numbers you should know.

[01:33:37]Is it clear?

[01:33:39]So this is for hydrogen. Had it been for helium plus what will be the change all the numbers will be multiplied by four >> Z square.

[01:33:50]>> If it is lithium + 2 all the numbers will be multiplied by 9. If it is berillium + 3 all the numbers will be multiplied by 16. Note so standard question n= 3 bilium + 3.

[01:34:07]What is the answer?

[01:34:09]Q square Z square by N square energy is proportional to Z square by N square right and recall that's why we are multiplying Z square term and zed for helium is 2 so zed square is four zed for lithium is 3 so zed square is 9 zed for berium is four so zed square is 16 nha shall and hay is that clear to all of you >> yes sir >> do you understand this now coming to your question the energy of an excited hydrogen atom is - 3.4 hydrogen case excited the answer.

[01:34:47]Is the question clear all of you? Anyone having any small issue also please discuss and ask questions practice questions key. Very good.

[01:35:00]Today we'll be doing spectrum also. So Lyman, Balmer, Passion, Bracket, Fun, Humphrey, Devi, all these series we'll do. We'll talk about lambda values, lambda max, lambda mination exam questions, right? We'll do that.

[01:35:49]Can we solve any difficult in this? Now let's say you come across a question where the question is lithium +2 electron goes from second to third orbit. Lithium plus2 electron goes from second to third orbit. How much energy will be required?

[01:36:11]How will you solve?

[01:36:13]Give me the answer. Lithium plus2 electron goes from second to third orbit. How much amount of energy will be involved?

[01:36:52]Just simply >> not hydrogen, lithium plus 2. So what will be the energy value? Huh?

[01:37:08]Minus 23 supply. So 17.1 check. Simple. See the gap of these two numbers. The gap of these two number is how much?

[01:37:22]Around 1.89.

[01:37:24]Check.

[01:37:26]This is 1.89. And this 1.89 multiplied by can I say 1.89 and multiplied by lithium. Lithium please come. Lithium is 9. So this will be your answer.

[01:37:41]Thirdly any issues hydrogen.

[01:37:53]Same question comes for Same question comes for hydrogen.

[01:38:00]Is it clear? We are talking about the energy of different levels. What is electron energy? As in n= 1 13.6 CV then further 3.4 then further 13.6 by 9 then by 16. So if you want to go to like here to here this is the gap. Okay. He ought to