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Some Basic Concepts of Chemistry

Multiple Choice Questions

111.

One mole of fluorine is reacted with two moles of hot concentrated KOH. The products formed are KF, H₂O and O₂. The molar ratio of KF, H₂O and O₂ , respectively is

1 : 1 : 2
2 : 1 : 0.5
1 : 2 : 1
2 : 1 : 2

112.

The electrochemical equivalent of a metal is 'x' g coulomb^-1. The equivalent weight of metal is

x
x × 96500
$\frac{x}{96500}$
1.6 × 10¹⁹ × x

113.

x grams of water is mixed in 69 g of ethanol. Mole fraction of ethanol in the resultant solution is 0.6. What is the value of x in grams?

114.

An organic compound containing C and H has 92.3% of carbon. Its empirical formula is

CH
CH₃
CH₂
CH₄

115.

x grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is 28 g. What is the value of x (in grams)?

116.
The concentration of oxalic acid is 'x' mol L^-1. 40 mL of this solution reacts with 16 mL of 0.05 M acidified KMnO₄. What is the pH of 'x' M oxalic acid solution ? (Assume that oxalic acid dissociates completely)

1.3

1.699

1

2

1.3

Oxalic acid = x mol/L

Oxalic acid = KMnO₄

M₁V₁ = M₂V₂

40 mL × x = 16 mL × 0.05

x = $\frac{16 \times 0.05}{40} = \frac{1}{50}$

x = $\frac{1}{50}$ M

Now, convert molarity into normality.

N × equivalent weight = M × molecular weight of oxalic acid

N × 45 = $\frac{1}{50} \times 90$

N = $\frac{1}{25}$

This normality represents the hydrogen ion concentration.

So, [H⁺] = $\frac{1}{25}$

pH = log $\frac{1}{[H^{+}]}$ = log 25 = 1.3

117.

Assertion (A): Equal moles of different substances contain same number of constituent particles.

Reason (R) : Equal weights of different substances contain the same number of constituent particles.

The correct answer is

Both (A) and (R) are true and (R) is the correct explanation of (A)
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(A) is true, but (R) is false
(A) is false but (R) is true

118.

Match the following:

List - I List - II

A. 10 gm CaCO₃ $\to_{decomposition}^{∆}$ (i) 0.224 L CO₂

B. 1.06 g Na₂CO₃ $\overset{Excess HCl}{\to}$ (ii) 4.48 L CO₂

C. 2.4 g C $\to_{Combustion}^{Excess O_{2}}$ (iii) 0.448 L CO₂

D. 0.56 g CO $\to_{combustion}^{Excess O_{2}}$
(iv) 2.24 L CO₂

(v) 22. 4 L CO₂

The correct match is

A - iv; B - i; C - ii; D - iii
A - v; B - i; C - ii; D - iii
A - iv; B - i; C - iii; D - ii
A - i; B - iv; C - ii; D - iii

119.

138 g of ethyl alcohol is mixed with 72 g of water. The ratio of mole fraction of alcohol to water is

3 :4
1: 2
1:4
1: 1

120.

1.5 g of CdCl₂ was found to contain 0.9 g of Cd. Calculate the atomic weight of Cd.

118
112
106.5
53.25

List - I	List - II
A. 10 gm CaCO₃ $\to_{decomposition}^{∆}$	(i) 0.224 L CO₂
B. 1.06 g Na₂CO₃ $\overset{Excess HCl}{\to}$	(ii) 4.48 L CO₂
C. 2.4 g C $\to_{Combustion}^{Excess O_{2}}$	(iii) 0.448 L CO₂
D. 0.56 g CO $\to_{combustion}^{Excess O_{2}}$	(iv) 2.24 L CO₂ (v) 22. 4 L CO₂

Previous Year Papers

Test Series

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Multiple Choice Questions

116. The concentration of oxalic acid is 'x' mol L-1. 40 mL of this solution reacts with 16 mL of 0.05 M acidified KMnO4. What is the pH of 'x' M oxalic acid solution ? (Assume that oxalic acid dissociates completely) 1.3 1.699 1 2

116.
The concentration of oxalic acid is 'x' mol L^-1. 40 mL of this solution reacts with 16 mL of 0.05 M acidified KMnO₄. What is the pH of 'x' M oxalic acid solution ? (Assume that oxalic acid dissociates completely)

1.3

1.699

1

2