11.

Which one of the following statements is not correct?

• Rydberg's constant and wave number have same units

• Lyman series of hydrogen spectrum occurs in the ultraviolet region

• The angular momentum of the electron in the ground state hydrogen atom is equal to $\frac{\mathrm{h}}{2\mathrm{\pi }}$

• The radius of first Bohr orbit of hydrogen atom is 2.116 × 10^-8 cm.

Which one of the following statements is correct?

• Bronsted-Lowery theory could not explain the acidic nature of BCl₃

• The pH of 0.01 M NaOH solution is 2.

• The ionic product of water at 25°C is 10^-10 mol²L^-2. 

• The pH of a solution can be calculated using the equation pH = log[H⁺].

One mole of A(g) is heated to 200°C in a one litre closed flask, till the following equilibrium is reached.

A(g) B(g)

The rate of forward reaction at equilibrium is 0.02 mol L^-1min^-1. What is the rate (in mol L-1min^-1) of the backward reaction at equilibrium?

• 0.04

• 0.01

• 0.02

• 1

The energy of an electromagnetic radiation is 19.875 × 10^-13 ergs. What is its wave number in cm^-1? (h = 6.625 × 10^-27 erg sec; c = 3 × 10¹⁰ cm sec^-1)

• 1000

• 10⁶

• 100

• 10000

At 27°C, a closed vessel contains a mixture of equal weights of helium (mol. wt. = 4), methane (mol, wt. = 16) and sulphur dioxide (mol. wt. = 64). The pressure exerted by the mixture is 210 mm. If the partial pressures of helium, methane and sulphur dioxide are p₁, p₂ and p₃ respectively, which one of the following is correct?

• p₃ > p₂ > p₁

• p₁ > p₂ > p₃

• p₁ > p₃ > p₂

• p₂ > p₃ > p₁

What is the hybridization state of the central atom in the conjugate base of NH${}_4^{+}$ ion?

• sp

• sp³

• sp²

• dsp²

Iron sulphide is heated in air to form A an oxide of sulphur. A is dissolved in water to give an acid. The basicity of this acid is

• 2

• 3

• 1

• zero

Calculate the heat of combustion (in kJ) of methane from the following data :

(i) C_(graphite) + 2H₂ (g) → CH₄ (g) ; $∆$H = -74.8 kJ

(ii) C_(graphite) + O₂ (g) → CO₂ (g) ; $∆$H = -393.5 kJ

(iii) H₂ (g) + 1/2 O₂ (g) → H₂O (l) ; $∆$H = -286.2 kJ

• -891.1

• -816.3

• -965.9

• -1040.7

Which one of the following statements is correct?

• The radius (R) of a nuclide of mass number A is given by the equation R = R₀(A)^1/2 (R₀ = constant)

• ₇N¹⁵ and ₈O¹⁶ are isobars

• The end product nuclide in thorium (4n) series is ₈₃Bi²⁰⁹

• ₂₀Ca⁴⁰ has magic number of protons and magic number of neutrons

Which one of the following is not an iso-electronic pair?

• Mg²⁺, C^4-

• N^3-, O^2-

• N^2-, O^2-

• F^-, Al³⁺