NH₄Cl (s) is heated in a test tube. Vapours are brought in contact with red litmus paper, which changes it to blue and then to red. It is because of

• formation of NH₄OH and HCl

• formation of NH₃ and HCl

• greater diffusion of NH₃ than HCl

• greater diffusion of HCl than NH₃

When 1 mole of CO₂ (g) occupying volume 10 L at 27°C is expanded under adiabatic condition, temeprature falls to 150 K. Hence, final volume is

• 5 L

• 20 L

• 40 L

• 80 L

Which of the following ligands is tetradentate?

A near UV photon of 300 nm is absorbed by a gas and then re-emitted as two photons. One photon is red with wavelength 760 nm. Hence, wavelength of the second photon is

• 1060 nm

• 496 nm

• 300 nm

• 215 nm

A constant current of 30 A is passed through an aqueous solution of NaCl for a time of 1.00 h. What is the volume of Cl₂ gas at STP produced?

• 30.00 L

• 25.08 L

• 12.54 L

• 1.12 L

If for the cell reaction,

Zn + Cu²⁺ $\rightleftharpoons$ Cu + Zn²⁺;

entropy change $∆\mathrm{S}°$ is 96.5 J mol^-1K^-1, then temperature coefficient of the emf of a cell is

• 5 × 10^-4 VK^-1

• 1 × 10^-3 VK^-1

• 2 × 10^-3 VK^-1

• 9.65 × 10^-4 VK^-1

What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition, n = 4 to n = 2 of He⁺ spectrum?

• n = 4 to n = 2

• n = 3 to n = 2

• n = 2 to n = 1

• n = 4 to n = 3

What is the degenercy of the level of H-atom that has energy $\left(-\frac{{\mathrm{R}}_{\mathrm{H}}}{9}\right)$ ?

• 16

• 9

• 4

• 1

What is the EAN of [Al(C₄O₄)₃]^3- ?

• 28

• 22

• 16

• 10

Calculate pH of a buffer prepared by adding 10 mL of 0.10 M acetic acid to 20 mL of 0.1 M sodium acetate [ pK_a (CH₃COOH) = 4.74 ]

• 3.00

• 4.44

• 4.74

• 5.04