The number of oxygen atoms in 4.4gm of CO₂ is

• 1.2 × 10²³

• 6 × 10²²

• 6 × 10²³

• 12 × 10²³

If the bond energies of H-H, Br-Br and H-Br are 433, 192 and 364 kJ mol^-1 respectively, then $∆$H° for the reaction-

H₂ (g) + Br₂ (g) → 2HBr (g) is

• -261 kJ

• +103 kJ

• +261 kJ

• -103 kJ

In the reaction,

Fe(OH)₃ (s) $\rightleftharpoons$ Fe³⁺ (aq) + 3OH^- (aq), if the concentration of OH^- ions is decreased by $\frac{1}{4}$ times, then the equilibrium concentration of Fe³⁺ will increase by

• 8 times

• 16 times

• 64 times

• 4 times

4.

The correct statement regarding entropy is

• at absolute zero temperature, entropy of a perfectly crystalline solid is zero

• at absolute zero temperature, the entropy of a perfectly crystalline substance is positive

• at absolute zero temperature, the entropy of all crystalline substances is zero

• at 0°C, the entropy of a perfect crystalline solid is zero

Equilibrium constants K₁ and K₂ for the following equilibria,

I. NO (g) + $\frac{1}{2}$ O₂ (g) $\rightleftharpoons$ NO₂ (g)

II. 2NO₂ (g) $\rightleftharpoons$ 2NO (g) + O₂ (g) are related as

• K₁ = $\sqrt{{\mathrm{K}}_2}$

• K₂ = $\frac{1}{{\mathrm{K}}_1}$

• K₁ = 2K₂

• K₂ = $\frac{1}{{\mathrm{K}}_1^2}$

The shape of XeF₆ is

• square planar

• distorted octahedral

• square pyramidal

• pyramidal

CO is a stronger ligand than Cl^-, because

• CO is a neutral molecule

• CO has $\mathrm{\pi }$-bonds

• CO is poisonous

• CO is more reactive

Which of the following sequence is correct regarding field strength of ligands as per spectrochemical series?

• SCN^- < F^- < CN^- < CO

• F^- < SCN^- < CN^- < CO

• CN^- < F^- < CO < SCN^-

• SCN^- < CO < F^- < CN^-

A liquid can exist only

• between triple and critical points

• at any temperature above melting point

• between melting and critical points

• between boiling and melting points

The energy of electron in the n^th Bohr orbit of H-atom is

• $-\frac{13.6}{{\mathrm{n}}^2} \mathrm{eV}$

• $-\frac{13.6}{\mathrm{n}} \mathrm{eV}$

• $-\frac{13.6}{\mathrm{n}4} \mathrm{eV}$

• $-\frac{13.6}{{\mathrm{n}}^3} \mathrm{eV}$