The vapour pressures of two liquids A and B in their pure states are in the ratio of 1: 2. A binary solution of A and B contains A and B in the mole proportion of 1 : 2. The mole fraction of A in the vapour phase of the solution will be

• 0.2

• 0.25

• 0.52

• 0.33

Which of the following statements is true?

• The total entropy of the universe is continuously decreasing

• The total energy of the universe is continuously decreasing

• The total energy of the universe remains constant

• The total entropy of the universe remains constant

13.

5 mL of 0.4 N NaOH is mixed with 20 mL of 0.1 N HCl.The pH of the resulting solution will be

• 7

• 8

• 5

• 6

On adding which of the following, the pH of 20 mL of 0.1 N HCl will not alter?

• 20 mL of distilled water

• 1 mL of 0.1 N NaOH

• 500 mL of HCl of pH =1

• 1 mL of 1 N HCl

The C-H bond and C-C bond in ethane are formed by which of the following types of overlap?

• sp²-s and sp²-sp²

• sp-s and sp-sp

• p-s and p-p

• sp³-s and sp³-sp³

At 300 K, a gaseous reaction A → B + C was found to follow first order kinetics. Starting with pure A, the total pressure at the end of 20 min was 100 mm of Hg. The total pressure after the completion of the reaction is 180mm of Hg. The partial pressure of A (in mm of Hg) is

• 90

• 180

• 80

• 100

Which one of the following has a magnetic moment of.1.75 BM?

• V³⁺

• Cr³⁺

• Fe³⁺

• Ti³⁺

The correct order of ionisation energy of C, N, O and F is

• C < N < O < F

• C < O < N < F

• F < O < N < C

• F < N < C < O

The correct set of four quantum numbers for the outermost electron of sodium (Z = 11) is

• 3, 1, 1, $\frac{1}{2}$

• 3, 2, 1, $\frac{1}{2}$

• 3, 0, 0, $\frac{1}{2}$

• 3, 1, 0, $\frac{1}{2}$

The equivalent mass of a certain bivalent metal is 20. The molecular mass of its anhydrous chloride is

• 111

• 55.5

• 75.5

• 91