Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.

(b) Rate constant ‘k’ of a reaction varies with temperature ‘T’ according to the equation:

`logk=logA-E_a/2.303R(1/T)`

Where E_a is the activation energy. When a graph is plotted for `logk Vs. 1/T` a straight line with a slope of −4250 K is obtained. Calculate ‘E_a’ for the reaction.(R = 8.314 JK⁻¹ mol⁻¹)

 A first order reaction takes 40 minutes for 30% decomposition. Calculate t_1/2 for this reaction. (Given log 1.428 = 0.1548)

How will you bring about the following conversions?

Propanone to propane

The complex ion `[Co(H_2O)_5 (ONO)]^(2+) `

(A) linkage isomer

(B) ionisation isomer

(C) co-ordination isomer

(D) geometrical isomer

Draw the structures of the following molecules: (HPO₃)₃

Write the chemical reaction involved in Wolff-Kishner reduction.

Arrange the following:

Aniline, p-nitroaniline, p-methylaniline - in the increasing order of their basic strength

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)

The rate constant for the first-order decomposition of H₂O₂ is given by the following equation:

`logk=14.2-(1.0xx10^4)/TK`

Calculate E_a for this reaction and rate constant k if its half-life period be 200 minutes.

(Given: R = 8.314 JK^–1 mol^–1)

What is the role of t-butyl peroxide in the polymerization of ethene?

Write the mechanism of free radical polymerization of ethene.

Predict the products of the following reactions :

Give reasons : n-Butyl bromide has higher boiling point than t-butyl bromide.

Write the structures of main products when aniline reacts with the following reagents : HCl

A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.

(log 2 = 0.3010)

Write the chemical equations involved when aniline is treated with the following reagents: HCI

The rate constant of a first order reaction increases from 2 × 10⁻² to 4 × 10⁻² when the temperature changes from 300 K to 310 K. Calculate the energy of activation (E_a).

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

Write the structures of the main products when acetone (CH₃ − CO − CH₃) reacts with the following reagent :

Zn − Hg/conc. HCl