The element ${}_{90}{}^{232}\mathrm{Th}$ belongs to thorium series. Which of the following will act as the end product of the series?

• ₈₂Pb²⁰⁸

• ₈₂Bi²⁰⁹

• ₈₂Pb²⁰⁶

• ₈₂Pb²⁰⁷

Consider the following reversible reactions,

N₂(g) + 3H₂(g) $\rightleftharpoons$ 2NH₃(g) (K₁)  ...(i)

N₂ (g) + O₂(g) $\rightleftharpoons$2NO (g) (K₂) ....(ii)

H₂ (g) + $\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) \rightleftharpoons {\mathrm{H}}_2\mathrm{O} \left(\mathrm{g}\right) \left({\mathrm{K}}_3\right) ....\left(\mathrm{iii}\right)$

The equilibrium constant for the reaction:

2NH₃(g) + $\frac{5}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\hspace{0.17em}\rightleftharpoons 2\mathrm{NO}\left(\mathrm{g}\right) + 3{\mathrm{H}}_2\mathrm{O} \left(\mathrm{g}\right)$ will be

• K₁ K₂ K₃

• $\frac{{\mathrm{K}}_1{\mathrm{K}}_2}{{\mathrm{K}}_3}$

• $\frac{{\mathrm{K}}_1{\mathrm{K}}_3^3}{{\mathrm{K}}_2}$

• $\frac{{\mathrm{K}}_2{\mathrm{K}}_3^3}{{\mathrm{K}}_1}$

The number of moles of sodium acetate to be added to 0.1 M acetic acid for the buffer to have a pH = 4.7 is [pK_a for acetic acid is 4.7]

• 0.2

• 0.4

• 0.1M

• None of these

If radius of first Bohr's orbit of hydrogen atom is 'x', then the de-Broglie wavelength of electron in 3rd orbit is nearly

• 2πx

• 6πx

• 9x

• x/3

Quantum numbers l = 2 and m= 0 represent the orbital

• d_xy

• d_x²-y²

• d_z²

• d_xz

Which of the following statements is false?
1. Non-bonding pairs occupy more space than bonding pairs.

2. The bonding orbitals in trigonal bipyramidal molecule are described as sp³d hybrids.

3. SnCl₂ has linear shape.

4. PCl${}_4^{+}$ and AlCl${}_4^{-}$ are isoelectronic.

• 1

• 2

• 3

• 4

Match List I with List II and select the correct answer using the codes.

• A   B   C   D

  4   2   1    3

• A   B   C   D

  3   1    2   4

• A   B   C   D

  1   3    4   2

• A   B   C   D

  1   2    3   4

Standard enthalpies of formation of O₃, CO₂, NH₃ and HI are 142.2, -393.2,- 46.2 and 25.9 kJ mol^-1 respectively. Decreasing order of their stability is

• HI > NH₃ > CO₂ > O₃

• NH₃ > CO₂ > HI > O₃

• CO₂ > NH₃ > HI > O₃

• O₃ > HI > NH₃ > CO₂

A drop of solution (volume 0.05 mL) contains 3 x 10^-6  mole H⁺. If the rate constant of disappearance of H⁺ is 1.0 x 10⁷ molL^-1 s^-1, how long would it take for H⁺ in drop to disappear?

• 4 × 10^-6 s

• 1× 10^-7 s

• 3× 10^-6 s

• 6 × 10^-9 s

First and second ionisation enthalpies of Mg are 737. 76 and 1450.73 J mol^-1 respectively. The energy required to convert all the atoms of magnesium to magnesium ions present in 24g of magnesium vapours is

• 24 kJ

• 2.188 kJ

• 12 kJ

• 4.253 kJ