🔥 D-Block Most Expected Questions for RE-NEET 2026 ⚡ | NCERT Line by Line 🧪 | Score 180+ 🚀

Indexé : 2026-05-21

[00:00:01]Hello all my dear students. Welcome back again to H S P and world of chemistry.

[00:00:05]Now, here the inorganic chemistry questions, conversion type, D block, okay? A little bit you can say that mediocre, moderate to tough questions. Tough means nothing, moderate, right? So, on your screen you can see everyone, this is the question.

[00:00:28]And this question is over here. Let me focus over here.

[00:00:34]You have to focus whatever I'm telling you in English, I will repeat in English, right? As well.

[00:00:40]So, see a light blue screen crystalline solid.

[00:00:45]What? A light green blue screen crystalline solid. Halcyon yellow blue eyes hypnotized like that.

[00:00:54]So, this salt you have to find out. You salt but I don't know CBC IT, right? I see CBC ID make a information there and they are doing all public.

[00:01:04]Let's see.

[00:01:06]The first information, it's aqueous solution gives brown PPT with alkaline K2HGI4. K2HGI4 alkaline.

[00:01:16]If you remember Nessler's reagent, I made one video yesterday only. Salt analysis.

[00:01:31]Which radical?

[00:01:33]Yes.

[00:01:35]Okay, I'm not going to tell you.

[00:01:38]You see four options are given over there.

[00:01:42]Second point, it's aqueous solution gives blue color with K3Fe(CN)6.

[00:01:55]Now, this is the its solution in CL gives white PPT with barium chloride.

[00:02:00]Now, the chart options may say up to answer 100% but I like Nana J. Neither I is got love you buddy. So, he will call me. Neither children is so what's the correct answer?

[00:02:13]So, she is so she is So, the correct answer is same same the correct answer is Mohr's salt. Why it is Mohr's salt?

[00:02:26]See, the first point is giving indication about ammonium.

[00:02:31]Ammonium radical with Nestler's reagent from brown color complex iodide of Millon's base HgOHgNH2I.

[00:02:44]If you watch my video on based on qualitative analysis, it's given over there.

[00:02:52]Now, so ammonium is there and this is Turnbull's blue color. Turnbull's blue color is given by ferrous. Turnbull's blue color.

[00:03:04]Blue color. Blue color. Remember that if ferric is there, it forms ferric ferrocyanide Prussian blue and ferrous forms Yes, Turnbull's blue. So, ferrous confirmed. Now, with ferrous confirmed, ammonium confirmed. So, ammonium and ferrous Mohr's salt and the formula of Mohr's salt is Fe SO4 NH4 whole twice SO4 6 * H2O. That says H2O.

[00:03:42]So, this is B option, right? Now, are you ready for second question? So, we look ready here.

[00:03:51]Let's see.

[00:03:54]In front of you, this is your second question. Sabhi log dekhiye. Jee bhar ke dekhiye second question ko. Aur aapki manzil hai E tak pahunchna. You have to find out what is E. This is directly NCERT based question. Yes. I made this question from NCERT lines, NCERT concept. Now, the correct answer is This is iron chromite ore. An iron chromite ore you can write in this way also, ferrous oxide and Cr2O3.

[00:04:30]Now, in this, Cr2O3 is in +3 oxidation state.

[00:04:36]Now, oxygen is electron snatcher. Oxygen is always luteri of electron. It will take electrons, all the electrons, and chromium will change into +6.

[00:04:48]+6 oxidation state. But, what compound will get formed with +6 oxidation state? Because sodium chromate is also +6.

[00:04:58]Sodium dichromate is also +6. CrO3 is also +6. So, remember that in basic medium, only chromate is stable.

[00:05:07]Dichromate is not stable. So, you will get Na2 CrO4. What I'm saying? Na2CrO4 is stable in basic medium. Stable in basic medium.

[00:05:20]Stable in basic medium. So, if you add acid, this acid H2SO4, it will change into dichromate.

[00:05:32]Na2 Cr2 O7.

[00:05:37]Potassium chromate is soluble in water as all sorts of ammonium, sodium, potassium, rubidium, cesium are soluble in water.

[00:05:45]So, potassium chromate and dichromate are soluble in water.

[00:05:50]And when you react with KCL, but let me tell you that this dichromate is orange colored. What colored? Orange. Hanuman Ji ka bhakt hota hai. Orange colored. Orange. This is orange colored.

[00:06:08]Soluble. And sodium chromate is yellow solution. Remember the color also.

[00:06:15]Yellow solution. And with KCL, it will do exchange reaction and you will get K2 Cr2O7.

[00:06:26]This is also orange solution. Orange solution. Remember that.

[00:06:34]Sodium dichromate, small cation, large anion.

[00:06:39]Small cation, large anion. So, small cation, large anion.

[00:06:45]That means its hydration energy will be more than lattice energy and it will be soluble in water. And that's why it is not used during volumetric analysis. But here, large cation, large anion. Stable. So, lattice energy is greater than hydration energy. It is not a deliquescent. The upper one was deliquescent and it is not deliquescent. Means will not absorb the moisture from the atmosphere. That's why it is used as primary standard potassium dichromate.

[00:07:21]All three, they're in sub Q oxidation state is plus six in all.

[00:07:29]ABC, plus six.

[00:07:32]That means there is no unpaired electron. The value of n is zero. But then also, they are colored. That means they are not colored due to DD transition. They are actually colored due to charge transfer spectra. So, color reason is colored due to charge transfer spectra and not due to DD transition.

[00:08:00]Now, pH 1 means highly acidic, then you will get red color CrO3.

[00:08:09]Here also, the oxidation state is +6.

[00:08:12]This is given in JD Lee. It is missing in It is missing in NCERT, but very, very important for your re-need JD Lee.

[00:08:24]Now, NaOH, I have told you what is stable in NaOH. So, NaOH, it will form yellow color solution sodium chromate, Na2CrO4, yellow solution. So, if you want to take screenshot, you can have it. So, this is Yes, the answer of this slide. Now, let's move towards another slide.

[00:08:53]Here is another question, you see.

[00:08:56]Try to do it yourself first of all.

[00:08:59]Pause the video.

[00:09:01]Try to find out the answer.

[00:09:11]Okay? Now, I'm going to explain the answer. Ready, kids? Everyone?

[00:09:18]So, see.

[00:09:24]So, let me copy it.

[00:09:31]So, first reaction, MnO2 KOH, MnO2 KOH So basic medium in basic medium green colored compound potassium manganate will get formed.

[00:09:49]Potassium manganate will form K2 MNO4, K2MNO4 because this is stable in basic medium. But as soon as you are adding neutral or alkaline medium, this manganese plus from plus six oxidation state will undergo oxidation as well as reduction. So it will form black colored PPT, black PPT of MNO2. It will form black PPT of MNO2 and you see in MNO2 the oxidation state is plus four as well as it will form KMnO4. KMnO4 is potassium permanganate KMnO4 oxidation state plus seven.

[00:10:37]So from plus six it is undergoing plus four that is being reduction and it is undergoing plus seven that is being oxidation. So this is a disproportionation reaction. Disproportionation very very important reaction my dear students. Now I negative when KMnO4 reacts with I negative in faintly alkaline medium. My dear students, mark my words it holds a hell lot of weightage and categorically I'm telling you this particular reaction. Very very important. It will form IO3 negative iodate. Remember that.

[00:11:18]IO3 negative iodate will definitely they will ask in the examination. Iodate. So this is clear. If you want to take screenshot of it you can have it. Okay?

[00:11:33]so this is well explained. Now another question on your screen. Just see to it.

[00:11:39]Swagat question see just try it yourself once you are not able to do it Baba H S P will help you chromite or if you don't know what is chromite or it is same f e c r 2 o 4 1 2 K 4 4 2 K 1 my name is iron chromite or now na2co3 h2so4 KCL up to here you know orange color which compound will get formed orange color do let me know orange color yes yes yes K2 cr2 07 will get formed and that on reaction with NaCl h2so4 will form reddish brown vapours of c r o 2 c l 2 very very important reaction.

[00:12:40]It is chromyl chloride gas chromyl chloride gas for this the test tube should remain dry otherwise chromic acid will get formed.

[00:12:52]It will react with water to form h2cro4 so test tube should remain dry test tube ekdum sookhi rehni chahiye usme pani nahi hona chahiye right now on reaction with NaOH it will form yellow color solution PB sorry sodium chromate and that will react with that is soluble and it will react with lead acetate to form pbcro4 yellow papita yellow PPT not soluble in water. So this is your answer.

[00:13:30]I hope you got it everyone loving these reactions, these conversions. Definitely very very important for the NEET now.

[00:13:39]Next slide, the next question. Let's see what is the next slide and what is the next question. And will you be able to do this question? This question too you have to do it.

[00:13:50]Now I have told you number of reactions.

[00:13:52]What the first reaction have you ever studied?

[00:13:57]KMnO4 KMnO4 is known as PPR. What do you mean by PPR? PPR means pink purple red.

[00:14:09]That depends on how much concentration of KMnO4 is there. PPR means pink, purple, red. And one more meaning of PPR, just try to decode decode it.

[00:14:21]Pink purple red. The another thing is that its name potassium permanganate because K2MnO4 is potassium manganate PM. This is PPR potassium permanganate and on heating it will change into black colored powder MnO2.

[00:14:43]Black powder MnO2 black colored powder MnO2.

[00:14:52]And plus it will form K2MnO4 K2 MnO4 green colored K2MnO4.

[00:15:04]Now this K2MnO4 is stable only in strongly basic medium. When you provide either neutral or acidic medium it will undergo disproportionation. Already I've told you to form black colored powder what? Black colored powder MnO2.

[00:15:23]black colored powder mno2 plus it will give what?

[00:15:29]Yes, yes, it will give what? Do let me know everyone. It will give kmno4 kmno4 pink purple or red kmno4 pink purple or red. Now I have told you in faintly alkaline medium it will form iodate but in acidic medium it will form iodine I2. So kmno4 is acting as strong oxidizing agent and I negative is acting as a reducing agent. So this is a redox reaction. I hope everyone you are doing at least 50% to you can do by yourself.

[00:16:08]Rest Baba is helping you a lot. So my dear students, now coming another question and this question if they are giving very tough then only.

[00:16:20]Very tough question is coming then only otherwise you can leave it. If you are getting more than 650 in your examination then only go for it. It's only for AIIMS Delhi students only for AIIMS Delhi students. If your मंजिल is to go to AIIMS Delhi, if you want to get the top 10 rank then you can go for it.

[00:16:46]Right? This is from J Mains.

[00:16:49]Now see answer I'm providing you. If you want to see you can see here is the answer.

[00:16:57]Cobalt chloride on reaction with H2S when you pass H2S gas from the Kipp's apparatus Kipp's apparatus you will get black colored PPT of COS.

[00:17:10]COS copper sulfide is black PPT on reaction with HCL you will get cobalt chloride.

[00:17:18]That will form cobalt cyanide and they will form complex, right?

[00:17:24]First of It is of plus two oxidation state then it is of plus three. So this is your final answer. So I hope this is the last slide. Yeah, this is the last slide. So kids, how was it?

[00:17:42]Everyone just do let me know in the comment section. This is the first conversion of inorganic chemistry. Most expected directly questions will come from here.

[00:17:54]Why?

[00:17:55]This is paper leaking? No, because I will let you know each and everything in different ways. So I am preparing you.

[00:18:03]I'm trying to give you the knowledge, not only the marks.

[00:18:10]All the best, kids.