# 214 - Chemistry Questions Answers

A sample of fuming HNO3 is labelled as 110% . assume that the labelling of fuming is similar the labelling of oleum . What is the % of free N2O5 in the sample??

plz annex explanatn also ans is 60%

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Joshi sir comment

x % HNO--------------------- 100 + (18/108)*x % of fuming HNO3

so 18x/108 = 10

or x = 60 %

If ionic product of water is Kw = 10-6 at 4°C, then a solution with pH = 7.5 at 4°C will

(i) turns blue litmus red

(ii) turns red litmus blue

(ii) Be neutral to litmus

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Joshi sir comment

question is not appropriate because for given Kw , [H+] will be 10-3 and max. pH will be 6 and the question is asking about a solution of pH 7.5 which is out of limit

but if it is considered as a correct question then answer will be (ii)

N2 + O2 = 2NO . Equilibrium constant Kc = 2 . Degree of dissociation is

(i)  1/1-√2   (ii) 1/1+√2    (iii) 2/1-√2

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Joshi sir comment

N2   +    O2   =    2NO

1                       1                       0

1-x                    1-x                  2x

so by formula Kc = (2x)2 / (1-x)(1-x)

now solve for x

In the equilibrium SO2Cl2 = SO2 + Cl2 at 2000K and 10 atm pressure , % Cl2 = % SO2 = 40 (by volume) . Then what is the value of Kp?

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Joshi sir comment

SO2Cl2 = SO2 + Cl2

100               0           0

20                  40       40

2 atm             4 atm   4 atm

now calculate Kp

0.2 mole of N2 and 0.6 mole of H2 react to give NH3 and 40 % of reactant mixture is decreased , according to the equation,

N2 (g) + 3H2 (g) =  2NH3 (g) at constant temperature and pressure. Then the ratio of the final volume to the initial volume of gases is

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Joshi sir comment

N2 (g) + 3H2 (g) =  2NH3 (g)

0.2          0.6                0

0.2-x       0.6-3x         2x

according to the given condition 4x = 0.8*40/100 = 0.32

so x = 0.08

now solve

1 mole of A , 1.5 mole of B and 2 moles of C are taken in a vessel volume one litre. At equilibrium concentration of C is 0.5 mole/L. Equilibrium constant for the reaction
A (g) + B (g) = C (g)

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Joshi sir comment

A (g) + B (g) = C (g)

1         1.5        2

1-x      1.5-x     2+x

according to the given condition 2+x = 0.5 so x = -1.5

now calculate Kc

The Ksp for a sparingly soluble Ag2CrO4 is 4 x 10-12. The molar solubility of the salt is

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Joshi sir comment

Ag2CrO-------------> 2Ag + CrO4

s                                            0                  0

2s                 s

so Ksp = (2s)2 s = 4s3

now solve

A 0.1N solution of sodium bicarbonate has a pH value of

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Joshi sir comment

Please submit complete question, Ka should be given with percentage of ionisation

pH of 0.1 M NH4Cl solution is

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Joshi sir comment

For calculating pH of a salt, only concentration is not sufficient

pH of 102 M HCl is

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