11.

The element with atomic number 12 belongs to .... group and .... period

• I A, third

• III A, third

• II A, third

• II A, second

Which of the following statements is true?

• Hybridisation of the central atom in NH₃ and CH₄ is sp²

• BeCl₂ has V shape while SO₂ is linear

• SF₆ is octahedral and F-S-F bond angle is 90°

• CO₂ has dipole moment

Bond dissociation energies of HF, HCl, HBr follow the order

• HCl > HBr > HF

• HF > HBr > HCl

• HF > HCl > HBr

• HBr > HCl > HF

What is the volume (in litres) of oxygen at STP required for complete combustion of 32 g of CH₄?

(Molecular weight of CH₄ is 16)

• 44.8

• 89.6

• 22.4

• 179.2

The r.m.s. velocity of CO₂ at a temperature T (in kelvin) is x cm s^-1. At what temperature (in kelvin), the r.m.s. velocity of nitrous oxide would be 4x cm s^-1? (Atomic weights of C, N and O are respectively 12, 14 and 16)

• 16 T

• 2 T

• 4 T

• 32 T

n moles of an ideal gas at temperature T (in kelvin) occupy V L of volume, exerting a pressure of P atmospheres. What is the concentration (in mol/L) ?

• $\frac{\mathrm{P}}{\mathrm{RT}}$

• $\frac{\mathrm{PT}}{\mathrm{R}}$

• $\frac{\mathrm{RT}}{\mathrm{P}}$

• $\frac{\mathrm{R}}{\mathrm{PT}}$

250 mL of a sodium carbonate solution contains 2.65 g of Na₂CO₃. If 10 mL of this solution is diluted to one litre, what is the concentration of the resultant solution ?

• 0.1 M

• 0.001 M

• 0.01 M

• 10^-4 M

The pK_a of a weak acid is 4.8. What should be the ratio of $\frac{\left[\mathrm{acid}\right]}{\left[\mathrm{salt}\right]}$, if a buffer of pH = 5.8 is required?

• 0.1

• 10

• 1

• 2

Which of the following would produce a buffer solution when mixed in equal volumes?

• 1 M CH₃COOH and 0.5 M NaOH

• 1 M CH₃COOH and 0.5 M HCl

• 1 M NH₄OH and 0.5 M NaOH

• 1 M NH₄Cl and 0.5 M HCl

Equilibrium constant for the reaction,

H₂O (g) + CO (g) $\rightleftharpoons$H₂ (g) + CO₂ (g) is 81.

If velocity constant of the forward reaction is 162 L mol^-1s^-1. What is the velocity constant (in L mol^-1s^-1) for the backward reaction?

• 13122

• 2

• 261

• 243