PHYSICAL CHEM TEST-10 VIDEO SOLUTION FOR RE NEET-2026

Añadido: 2026-06-05

[00:00:00]Goal Nations [Music] Leading Institute.

[00:00:07]Hello Students, I am Deepak Deep going to discuss Physical Chemistry Part of Test No. 10 of Test Series for REET 2026 and it was held on 2nd June 2026. Ah let's start with the first question of Physical Chemistry and it is question number 138 on the board. You focus on question number 138 on the board. Question number 138 is children half filled and fully filled degenerate orbitals are more stable. That's correct. Half filled and fully filled orbitals are more stable. You already know this. And the reason given for this is that extra stability is due to symmetrical distribution of electrons and exchange energy. Brother, due to whom will there be stability? Because the exchange energy will be high and there is a symmetric configuration. There is a symmetric distribution in that degenerate orbital. So the answer is the first one is correct, the second one is also correct and there is an explanation also. So let's answer the third one. The answer to 138 will be three.

[00:01:14]After question number 138, see question number 146 on the board.

[00:01:20]A compound mx2 has observed and normal molar masses like given. Calculate apparent degree of ation.

[00:01:30]This is the question for the solution chapter. You can tell kids that [sound of clearing throat] the want of factor is the molar mass theoretically by the molar mass absorbed.

[00:01:44]So if we solve this 164 / 65 5 then our value comes out to be 2.5. And for a salt like MX2, if it ionizes it will give three ions, so its i will be 1 + 2 alpha. Meaning 1 + 2 alpha = 2.5 so alpha is 1.5 / 2 and that is 75 so the percentage will be 75%. So the answer of 146 will be the first one. You have read about want of factor in solution and colligative property.

[00:02:23]This is a question based on that.

[00:02:26]After question number 146, please see 148.

[00:02:30]What is the degree of dissociation of weak acid HA having concentration one molar in the presence of strong acid HB?

[00:02:40]Brother, if you write K for HA, then K will be the concentration of H positive multiplied by the concentration of A negative divided by the concentration of HA and if you add a strong acid HB, then the value of KA is 10 to the power of -6, but H positive is mainly given by strong acid and that is one molar, I can write it as 1 * alpha C alpha and divide by C, children, C is given as one. So one is cancelled by one.

[00:03:13]So alpha comes out to be 10 power -6/1 and that will be 10 power -5. Meaning the basic concept is that I highlight its concentration.

[00:03:26]I replaced it with C alpha and replaced it with C because 1 - alpha would be almost zero. The weak acid which was ionizing less earlier will ionize further in the presence of strong acid. In the presence of strong acid, common ion effect will be reported and I have applied that in it. So the answer will be 10 to the power of -5 first will be the answer. First answer of 148, after 148 you can see question number 149.

[00:03:56]149 is saying what mass of calcium chloride in grams would be enough to [sound of clearing throat] produce 14.5 grams 14.35 grams of AgCl brother AgCl you know that the molar mass of silver chloride would be 143.5 grams.

[00:04:15]And the molar mass of calcium chloride will be your triple1 gram. In other words, if you look at the chlorine in it, there is only one chlorine. If you look at the chlorine in it, there are two chlorines.

[00:04:26]Meaning we are able to understand that if there is triple one gram calcium chloride then there is 71 grams of chlorine in it brother. And [sound of clearing throat] how much mass does it require? I have asked. How much chlorine do we need? Let's see. Let's look at the first requirement from here.

[00:04:45]AgCl has 143.5 molar mass. If there is this much gram of AgCl then there is 35.5 grams of chlorine in it. So if this 3.5 [sound of clearing throat] if we change it to three 35.5 grams of chlorine 14.35, then we change it by one decimal. There will be 3.55 grams of chloride. So for 14.35 grams, we need this much chlorine 3.55. So brother, if there was a demand for triple 1 gram for 71 grams, then 35.5 grams of chlorine, then this became half of ours [sound of clearing throat], so this also became half. 55 grams of calcium chloride would be required. So if we need 3.55 grams of chlorine, we'll move one more decimal. The answer will be 5.55 grams. So this will come from 55.5 to 5.55. So what should be the answer to this? Forest. Meaning, I have applied atom conservation to the basic concepts, children. I conserved the chlorine and I saw it with the chlorine.

[00:05:54]What was one thing common between calcium chloride and AgCl? Chlorine.

[00:05:56]So by commonizing chloride we applied POA.

[00:06:00]You do it like this. Principle of Conservation of Atoms.

[00:06:04]After question number 149, you should see 153. A Solution Has PA Five. Having pH five means the child has become H positive, the acid which is giving 10 to the power -5 and you have diluted it 100 times, so suppose it was 1 litre, now if I make the volume 100 litres, then how much will the new H positive be, so if we apply m1 v 1 m2 v 2, then 10 to the power -5 * 1 = 100 * new H positive, so H positive has come, the acid which is giving 10 to the power -7 and H positive water is also giving 10 to the power -7, so the net solution which will be there will now have H positive approximately 2 * 10 to the power -7, so the pH will be 7 - log2.

[00:06:57]So what was more acidic before will now become a little less acidic in five.

[00:07:02]So the answer is less acidic.

[00:07:09]After the third answer 153, you can see question number 155. A mono basic weak acid solution has a molarity of 0.05 molar and a pH of five. What is the percentage of this solution? Molarity is given children and PA is given. Brother, after giving PA you are telling me that five is h positive, I understood that 10 to the power of -5 and h positive c is alpha. Meaning c alpha 10 power -5 so alpha 10 power -5 / 5 * 10 power -3 10 power -3 to the power of 10 -2 so here we go [sound of clearing throat] 5 is 2 * 10 power -3 percentage ionization what will happen child multiply alpha by 100 so 2 * 10 power -3 * by 100% and that will be 2% so the answer should be ah second percentage second will become.

[00:08:10]You also asked this ionic equilibrium based question of PA. There is also H positive C alpha. It is K * C. We use requirements on edge. For now we'll use C alpha.

[00:08:22]After question number 155, please see 157.

[00:08:25]How many grams of silver will be displaced from a solution of AgNO3 by 4 grams of magnesium? Brother [sound of clearing throat] equivalents equalize. Meaning we can equalize the number of equivalents of mg.

[00:08:42]Number of equivalents of silver can. Magnesium is four whose equivalent mass is 12. We have to find its weight whose molar mass is 108/1 valency. So W comes out to be 108 / three so 36 of 3 * 3 is 108 so the answer is 36 grams third answer you could have done with mole concept also. You can also do this by balancing the equation.

[00:09:14]So whatever you think is right, equating equivalents is the most basic method. This is the easiest way. It is the Elementary Way. So I think this is understandable. Question number 157 is followed by 159. 500 ml of 0.1 molar acetic acid plus 500 ml of 0.2 molar ah CH3CO gives a pKa = 5.3 brother it is a weak acid and its salt means it is a buffer so the pH will be equal to pKa + log concentration of CH3COON divided by concentration of CH3COOH pKa you have given 5.3 let us find out pKa. The concentration of log sodium acetate by 5 is half a litre solution divided by volume, so since it will get cancelled out, I am not writing the volume, I am writing the equivalents below 01 * 5, so this will get cancelled out, if this becomes log2 then pka will come out to 5 brother, the value of log2 is 3, so the difference will come out to 3 from here and if PK comes out then our pKB will become nine. So the answer should be nine.

[00:10:40]Second answer temperature we assumed children 25° Celsius. If temperature is not given then it is considered as standard condition.

[00:10:50]After question number 159, please see 160.

[00:10:54]36 grams of magnesium will react completely with hydrochloric acid to give. Let's do it by balancing the equation. Could have done it with equivalent also. If the child reacts with MgCl, it will give MgCl2 and H2. Now if we balance it, it becomes two.

[00:11:10]Meaning if it was 24 grams, you would get 1 mole. We have to answer this question in detail.

[00:11:17]So if this is 36 grams times 1.5, then this is also going to be 1.5 times 3/2 moles.

[00:11:24]So the answer is 3/2 mole of hydrogen will be the answer of 160 seconds. It was done through the Mole concept.

[00:11:32]You can also do this by equating gram equivalents.

[00:11:35]Like I did before. So apply both the methods now, you will understand both in the solution.

[00:11:43]After question number 160, please see 162.

[00:11:47]Which solution will show maximum elevation in boiling point? Brother, we are talking about elevation boiling point i.e. delta TB which is I * KB * M. Delta TB will be maximum when I is maximum.

[00:12:01]And I will be higher for the one which has higher number of ions. So I is its brother two.

[00:12:08]I is its four. I Its three but its five. So the highest I is of fourth. So the maximum elevation will be in the fourth.

[00:12:17]Solution chapter question. This is also an easy question. Want of factor based questions, please see question number 162 and then 165. The degree of hydrolysis of certain anions is given like D is the highest, D is the negative is the lowest. If you know the concept of hydrolysis, children, then hydrolysis will be maximum for that ion which is a strong conjugate ion. The strong conjugate ion would be the one that came from the week.

[00:12:47]I understood that if HA, HB, HC and HD are acids then the order of their acidic strength is something like this. If HD has the lowest order of acidic strength, then its KA will be the smallest.

[00:13:05]Its KA will be the smallest and pKA will be the largest. You are asking me about maximum PK, so what will I answer? Fourth. I mean, you were asking me, in a way, who would be the Weakest Acid Among These? So it is understandable that the weakest conjugate pair will be hydrolyzed the most.

[00:13:29]See question number 165 followed by 167. This is a matrix matching based question. Let's make the match.

[00:13:36]What does the principal quantum number tell us? So what happens? So what could be any positive integer 1 2 3 azimuthal quantum number? So the azimuthal quantum number is the value of l that goes up to n - 1. The magnetic quantum number is - l2 + l including zero. And the spin quantum number but obviously it will be p. So A's R A's R B's Q C's [throat clearing sound] s. This is the first answer. The first answer is matching.

[00:14:13]You can see it on the board. So I think it's easy. It is a simple question. Structure of Atom Quantum Number Topic.

[00:14:22]After question number 167, please see 168.

[00:14:26]For a reaction of order n the units of rate constant change with the order of the reaction. Order n is given children. And it is saying that different K will have different units.

[00:14:37]So it makes sense that r = ka to the power n would be children. So you say the unit of K is mole per liter per second, on the top mole per liter per second and on the bottom side we get mole per liter to the power n, so the unit of k becomes mole per liter to the power 1 - n per second, so the unit of k will be different for different orders, it is understandable, the first one is correct, for a first order the half life is independent of the initial concentration of the reactant. This is also correct because the t half of the first order, baby, is 693 / k. There is no initial concentration in this.

[00:15:21]Meaning it will not depend on the initial concentration. Whatever the initial concentration t half the Riemann constant. So first is right, second is right but quite two independent statements. So the assertion is correct, the reason is correct but the explanation is not.

[00:15:37]Such an answer is seconds. So let's answer the second answer of 168.

[00:15:47]You can see 171 after question number 16 8.

[00:15:51]171 Spontaneous reaction is impossible if. When is there not a reaction, brother? When deltaH is positive and deltaS is negative.

[00:16:03]So in such a situation, delta g is delta H - T delta. If this is positive and this is negative then this will become positive.

[00:16:12]Meaning it will always be positive at any temperature and if DeltaG becomes positive then the child process will be non-spontaneous.

[00:16:21]So this is a condition where deltaH is positive endothermic with decreasing randomness, it can never be spontaneous. So let's answer.

[00:16:29]Delta h is positive and Delta is negative. The process is impossible.

[00:16:37]After 171, you can see 172. Match the electrochemical concept with their correct description. What does a galvanic cell do, brother? Converts chemical energy into electrical energy. What does an electrolytic cell do? Electrical energy is used to drive a non-spontaneous reaction. What does nonsticking do brother? It is a mathematical expression used to calculate electrode potential. Salt bridge is used to maintain electrical neutrality. So match it.

[00:17:09]S of A comes in two places, two and four of B, q of B, so obviously the second answer is yours. The rest must be matching because B is differentiating here. So this was a matrix matching of electrochemistry and the overall concept is of electrochemistry.

[00:17:27]See all the question numbers 172 to 177. You can see the board question dx/dt is k dx/dt and someone is saying rate, child, the rate is k h positive to the power n and you are saying pA to one, then it becomes 100 times. Brother, when pA was two, then h was positive to the power of 10 -2. When pA became one, then h became positive to the power of 10 -1.

[00:17:55]Meaning, how many times are you increasing the concentration of hydrogen ions? 10 times. Here I am doing concentration 10 times and here it is happening 100 times. Meaning, what power of 10 will be 100? So the value of n is two understandable. The second answer will be 177.

[00:18:15]This was a question on chemical kinetics. It was related to PA.

[00:18:20]You can call it a mixed question of ionic equilibrium kinetics. So this was your Physical Chemistry paper. Hope you did it right. Thank you so much.