The unit of rate constant for a zero-order reaction is:

1. ${\mathrm{s}}^{-1}$

2. $\mathrm{mol}$ ${\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$

3. $\mathrm{L}$ ${\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$

4. ${\mathrm{L}}^2{\mathrm{mol}}^{-2}{\mathrm{s}}^{-1}$

The half-life of a certain enzyme catalysed reaction is 138 s, that follow the 1st order kinetics. The time required for the concentration of the substance to fall from 1.28 mg L^–1 to 0.04 mg L^–1, is:

1. 276 s 

2. 414 s

3. 552 s 

4. 690 s

Consider the following processes:

                                       ∆H (kJ/mol)
½ A → B                            + 150
3B → 2C + D                      –125
E + A → 2D                        +350

For B + D → E + 2C, ∆H will be:

1. 325 kJ/mol 

2. 525 kJ/mol

3. –175 kJ.mol 

4. –325 kJ/mol

Which of the following pairs of oxygen species and their magnetic behaviour is correct?

1. $\mathrm{O},$ ${\mathrm{O}}_2^{2-}$ - Both paramagnetic
2. ${\mathrm{O}}_2^{-},$ ${\mathrm{O}}_2^{2-}$ - Both diamagnetic
3. ${\mathrm{O}}^{+},$ ${\mathrm{O}}_2^{2-}$ - Both paramagnetic
4. ${\mathrm{O}}_2^{+},$ ${\mathrm{O}}_2$ - Both paramagnetic

According to the Bohr Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon?
1. n = 5 to n = 3
2. n = 6 to n = 1
3. n = 5 to n = 4
4. n = 6 to n = 5

In qualitative analysis, the metals of Group I can be separated from other ions by precipitating them as chloride salts. A solution initially contains Ag⁺ and Pb²⁺ at a concentration of 0.10 M. Aqueous HCl is added to this solution until the Cl^– concentration is 0.10 M. What will the concentration of Ag⁺ and Pb²⁺ at equilibrium?
(K_sp for AgCl  = 1.8 × 10^-10)$$
(K_sp for PbCl₂ = 1.7 × 10^-5) 

A bubble of air is underwater at a temperature15°C and the pressure 1.5 bar. If the bubble rises to the surface where the temperature is 25°C and the pressure is 1.0 bar, what will happen to the volume of the bubble?

1. Volume will become greater by a factor of 2.5
2. Volume will become greater by a factor of 1.6
3. Volume will become greater by a factor of 1.1
4. Volume will become smaller by a factor of 0.70

A 0.1 molal aqueous solution of a weak acid (HA) is 30 % ionized. If K_f for water is 1.86 °C/m, the freezing point of the solution will be:

A solution contains Fe²⁺, Fe³⁺ and I^– ions. This solution was treated with iodine at 35^°C. E° for Fe³⁺/Fe²⁺ is +0.77 V and E° for I₂/2I^– = 0.536 V.
The favourable redox reaction is:

1. Fe²⁺ will be oxidized to Fe³⁺.

2. I₂ will be reduced to I^–.

3. There will be no redox reaction.

4. I^– will be oxidized to I₂.

The rate of the reaction $2{\mathrm{N}}_2{\mathrm{O}}_5\to 4{\mathrm{NO}}_2+{\mathrm{O}}_2$ can be written in three ways:

$\frac{-d\left[N_2{O}_5\right]}{dt}=k\left[N_2{O}_5\right]$

$\frac{d\left[N{O}_2\right]}{dt}=k\text{'}\left[N_2{O}_5\right]$

$\frac{d\left[O_2\right]}{dt}=k\text{'}\text{'}\left[N_2{O}_5\right]$

Find out the relationship between k and k′ and between k and k′′:

1. k′ = k, k′′= k 

2. k′= 2k; k′′= k

3. k′= 2k, k′′= k/2 

4. k′ = 2k; k′′= 2k