HSC Science (Computer Science) 12th Standard Board Exam - Maharashtra State Board Important Questions

Write molecularity of the following reaction:

2NO_(g)+O_2(g)→2NO_2(g)

For a reaction: 

Rate = k

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.

The rate constant of a first order reaction increases from 4 × 10⁻² to 8 × 10⁻² when the temperature changes from 27°C to 37°C. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

A first order reaction takes 23.1 minutes for 50% completion. Calculate the time required for 75% completion of this reaction.

(log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021)

What are fuel cells?

0.05 M NaOH solution offered a resistance of 31.6 Ω in a conductivity cell at 298 K. If the cell constant of the cell is 0.367 cm^-1, calculate the molar conductivity of NaOH solution.

In the Arrhenius equation for a first order reaction, the values of ‘A’ of ‘E_a’ are 4 × 10¹³ sec⁻¹ and 98.6 kJ mol⁻¹ respectively. At what temperature will its half life period be 10 minutes?

[R = 8.314 J K⁻¹ mol⁻¹]

The unit of rate constant for zero order reaction is _______.

(A) t^–1

(B) mol dm^–3 t^–1

(C) mol^–1 dm³ t^–1

(D) mol^–2 dm⁶ t^–1

Construct a labelled diagram for the following cell:

`Zn|Zn^(2+)(1M)||H^+(1M)|H_(2(g,1atm))|Pt`

Which among the following reactions is an example of a zero order reaction?

a) `H_(2(g)) + I_(2(g)) -> 2HI_(g)`

b) `2H_2O_(2(l)) -> 2H_2O_(l) + O_(2(g))`

c) `C_12H_22O_(11(aq)) + H_2O_(l) -> C_6H_12O_(6(aq)) + C_6H_12O_(6(aq))`

d) `2NH_(3g)`   `N(2g) + 3H_(2(g))`

The rate constant of a first order reaction are 0.58 S^-1 at 313 K and 0.045 S^-1 at 293 K. What is the energy of activation for the reaction?

Calculate activation energy for a reaction of which rate constant becomes four times when temperature changes from 30 °C to 50 °C. (Given R = 8.314 JK⁻¹ mol⁻¹). 

How does calcination differ from roasting?

Write resonating structures of ozone.

The decomposition of N₂O_5(g) at 320K according to the following equation follows first order reaction:

`N_2O_(5(g))->2NO_(2(g))+1/2O_(2(g))`

The initial concentration of N₂O_5(g) is 1.24 x 10^-2 mol. L-1 and after 60 minutes 0.20x10^-2 molL^-1. Calculate the rate constant of the reaction at 320K.

Write cathode and anode reaction in a fuel cell.

The half-life period of zero order reaction A → product is given by

(a) `([A]_0)/k`

(b) `0.693/k`

(c) `[A]_0/(2k)`

(d) `(2[A]_0)/k`

How many faradays of electricity are required to produce 6 g of Mg from MgCl₂?

The half life period of a first order reaction is 6. 0 h . Calculate the rate constant

The molar conductivity of 0.05 M BaCl₂ solution at 25° C is 223Ω^-1 cm² mol^-1. What is its conductivity?