Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion (A): Electron gain enthalpy of oxygen is less than that of Flourine but greater than Nitrogen.

Reason (R): Ionisation enthalpies of the elements follow the order Nitrogen > Oxygen > Fluorine.

Select the most appropriate answer from the options given below:

The correct order of the packing efficiency in different types of unit cells is ______.

The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc and simple cubic unit cell are respectively ______.

Assertion: The total number of atoms present in a simple cubic unit cell is one.
Reason: Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells.

If two liquids A and B form minimum boiling azeotrope at some specific composition then ______.

Intermolecular forces between two benzene molecules are nearly of same strength as those between two toluene molecules. For a mixture of benzene and toluene, which of the following are not true?

(i) ∆_mix H = zero

(ii) ∆_mix V = zero

(iii) These will form minimum boiling azeotrope.

(iv) These will not form ideal solution.

Concentration terms such as mass percentage, ppm, mole fraction and molality are independent of temperature, however molarity is a function of temperature. Explain.

Why soda water bottle kept at room temperature fizzes on opening?

What is “semi permeable membrane”?

Assertion: Molarity of a solution in liquid state changes with temperature.

Reason: The volume of a solution changes with change in temperature.

Assertion: When a solution is separated from the pure solvent by a semipermeable membrane, the solvent molecules pass through it from pure solvent side to the solution side.

Reason: Diffusion of solvent occurs from a region of high concentration solution to a region of low concentration solution.

Explain the terms ideal and non-ideal solutions in the light of forces of interactions operating between molecules in liquid solutions.

In the electrolysis of aqueous sodium chloride solution which of the half cell reaction will occur at anode?

What will happen during the electrolysis of aqueous solution of \[\ce{CuSO4}\] by using platinum electrodes?

(i) Copper will deposit at cathode.

(ii) Copper will deposit at anode.

(iii) Oxygen will be released at anode.

(iv) Copper will dissolve at anode.

What will happen during the electrolysis of aqueous solution of CuSO₄ in the presence of Cu electrodes?

(i) Copper will deposit at cathode.

(ii) Copper will dissolve at anode.

(iii) Oxygen will be released at anode.

(iv) Copper will deposit at anode.

Aqueous copper sulphate solution and aqueous silver nitrate solution are electrolysed by 1 ampere current for 10 minutes in separate electrolytic cells. Will the mass of copper and silver deposited on the cathode be same or different? Explain your answer.

Assertion: Electrolysis of NaCl solution gives chlorine at anode instead of O₂.

Reason: Formation of oxygen at anode requires overvoltage.

Consider the figure and answer the following question.

Cell ‘A’ has E_Cell = 2V and Cell ‘B’ has E_Cell = 1.1V which of the two cells ‘A’ or ‘B’ will act as an electrolytic cell. Which electrode reactions will occur in this cell?

In the extraction of chlorine by electrolysis of brine ______.

Which of the following reactions is an example of autoreduction?