The pair, that is referred as 'chemical twins' is

• Ac, Cf

• Hf, Ta

• Tc, Re

• La, Ac

12.

The number of hydroxyl ions in 10 cm³ of 0.2 M HCl solution is

• 5 × 10^-14

• 3 × 10⁹

• 3 × 10¹²

• 5 × 10^-12

Heat of combustion of methane is -800 kJ. What is the heat of combustion for 4 × 10^-4 kg of methane?

• -800 kJ

• -3.2 × 10⁴ kJ

• -20 kJ

• -1600 kJ

Which of the following travels with the speed of light?

• α-rays

• β-rays

• γ-rays

• X-rays

Kirchhoff's equation is

• $\log \frac{{\mathrm{k}}_2}{{\mathrm{k}}_1} = \frac{{\mathrm{E}}_{\mathrm{a}}}{2.303 \mathrm{R}} \left[\frac{1}{{\mathrm{T}}_1} - \frac{1}{{\mathrm{T}}_2}\right]$

• $\log \frac{{\mathrm{p}}_2}{{\mathrm{p}}_1} = \frac{∆{\mathrm{H}}_{\mathrm{v}}}{2.303 \mathrm{R}} \left[\frac{{\mathrm{T}}_2 - {\mathrm{T}}_1}{{\mathrm{T}}_1 \times {\mathrm{T}}_2}\right]$

• $∆{\mathrm{C}}_{\mathrm{p}} = \frac{∆{\mathrm{H}}_2 - ∆{\mathrm{H}}_1}{{\mathrm{T}}_2 - {\mathrm{T}}_1}$

• $\text{log }\frac{{\mathrm{k}}_2}{{\mathrm{k}}_1} = \frac{∆\mathrm{H}}{2.303 \mathrm{R}} \left[\frac{1}{{\mathrm{T}}_1} - \frac{1}{{\mathrm{T}}_2}\right]$

When 10 A current is passed for 80 min, the volume of hydrogen gas liberated is

• 11.14 L

• 5.57 L

• 22.4 L

• 2.78 L

The IUPAC name of crotonaldehyde is

• butenaldehyde

• butanal-1

• but-2-en-1-al

• prop-2-en-1-ol

Willemite is

• Zn₂SiO₄

• H₂PtCl₆

• ZnO

• ZnOFe₂O₃

Which of the following compounds is optically active?

• Butanal

• Butanol

• Butan-2-ol

• 2-methyl propan-2-ol

Ethylidene dichloride is obtained by the reaction of excess of HCl with

• ethylene

• acetylene

• propene

• methane