Problem 11
In the ionic compounds the oxidation number of an ion (1) is the same as the charge of the ion. (2) is the same as the charge of the ion with opposite sign (3) is always zero (4) cannot be inferred from the formulae of the compounds
Problem 14
One mole of \(\mathrm{N}_{2} \mathrm{H}_{4}\) loses 10 moles of electrons and form \(\mathrm{y}\) which retain all nitrogen and hydrogen present in the original compound. Assuming that there is no change in the oxidation state of hydrogen, the change in oxidation state of nitrogen will be from (1) \(+2\) to \(+5\) (2) \(-2\) to \(+3\) (3) \(+3\) to \(+5\) (4) \(+2\) to \(+4\)
Problem 15
Which of the following statement is false? (1) In a conjugate pair of reduetant and oxidant the reductant has lowest oxidation number. (2) In a conjugate pair of reductant and oxidant the oxidant has higher oxidation number. (3) When an clement is oxidiscd its oxidation number increases. (4) In the reaction with lithium, hydrogen is oxidised.
Problem 16
Which is incorrect about oxidation? (1) deelectronation (2) inereased electron density (3) increase in oxidation state (4) loss of hydrogen
Problem 17
Reductants are substances which (1) Show increase in their oxidation number during a change. (2) Lose electrons during a change. (3) Reduce other and oxidise themsclves. (4) All.
Problem 18
The oxidation number and covalency of sulphur in the sulphur molecule \(\left(\mathrm{S}_{8}\right)\) are respectively (1) 0 and 2 (2) \(+6\) and 8 (3) 0 and 8 (4) \(+6\) and 2
Problem 19
Addition of zinc powder to copper sulphate solution precipitates copper due to (1) Reduetion of \(\mathrm{Cu}^{2+}\) (2) Reduction of \(\mathrm{SO}_{4}^{2-}\) (3) Reduction of \(\mathrm{Zn}^{2+}\) (4) Hydrolysis of \(\mathrm{CuSO}_{4}\)
Problem 20
The violent reaction between sodium and water is an example of (1) Reduction (2) Oxidation (3) Redox reaction (4) Neutralisation reaction
Problem 24
Magnesium reacts with acids producing hydrogen and corresponding magnesium salts. In sueh reactions, magnesium undergoes (1) Oxidation (2) Reduction (3) Neither oxidation nor reduction (4) Simple dissolution
Problem 27
Which statement is incorrect? (1) Oxidation of a substance is followed by reduction of another. (2) Reduction of a substance is followed by oxidation of another. (3) Oxidation and reduction are complimentary reactions. (4) It is not necessary that both oxidation and reduction should takes place in the same reaction.
