In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with:

1. Copper(l) sulphide (Cu₂S)

2. Sulphur dioxide (SO₂)

3. Iron Sulphide (FeS)

4. Carbon monoxide (CO)

An interstitial compound among the following is:

1. Invar

2. Steel

3. Bell metal

4. Bronze

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?Redox Reactions

1. S

2. H

3. Cl

4. C

Which one of the following alkali metals forms only the normal oxide M₂O on heating in air?

1. Rb

2. K

3. Li

4. Na

The ease of adsorption of the hydrated alkali metal ions on ion-exchange resins follows the order:

1. $L{i}^{+}<K^{+}<N{a}^{+}<R{b}^{+}$

2. $R{b}^{+}<K^{+}<N{a}^{+}<L{i}^{+}$

3. $K^{+}<N{a}^{+}<R{b}^{+}<L{i}^{+}$

4. $N{a}^{+}<L{i}^{+}<K^{+}<R{b}^{+}$

The incorrect statement among the following regarding photochemical smog is:

CH₃CHO and C₆H₅CH₂CHO can be distinguished by:

1. Benedict test

2. Iodoform test

3. Tollen's reagent test

4. Fehling solution test

Which of the following statements is false? 

The standard enthalpy of vaporization ${∆}_{\mathrm{vap}}{\mathrm{H}}^{\mathrm{o}}$ for water at 100 ^oC is 40.66 kJ mol^–1. The internal energy of vaporization of water at 100 ^oC (in kJ mol^–1) is: 
(Assume water vapour behaves like an ideal gas.)

Identify the incorrect statement among the following: