Problem 58
What is the oxidation number of carbon in \(\mathrm{C}_{3} \mathrm{O}_{2}\) (carbon suboxide)? (a) \(+4 / 3\) (b) \(+10 / 4\) (c) \(+2\) (d) \(+2 / 3\)
Problem 59
What is the oxidation number of carbon in \(\mathrm{C}_{3} \mathrm{O}_{2}\) (carbon suboxide)? (a) \(+4 / 3\) (b) \(+10 / 4\) (c) \(+2\) (d) \(+2 / 3\)
Problem 63
If \(\mathrm{Mn}^{3+}\) ions are unstable in solution and undergo disproportionation to give \(\mathrm{Mn}^{2+}, \mathrm{MnO}_{2}\) and \(\mathrm{H}^{+}\) ions. What will be the balanced equation for the reaction? (a) \(3 \mathrm{Mn}^{3+}+4 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{MnO}_{2}+\mathrm{Mn}^{2+}+8 \mathrm{H}^{+}\) (b) \(\mathrm{Mn}^{3+}+4 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{MnO}_{2}+4 \mathrm{H}^{+}\) (c) \(\mathrm{Mn}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{MnO}_{2}+4 \mathrm{H}^{+}\) (d) \(2 \mathrm{Mn}^{3+}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{MnO}_{2}+\mathrm{Mn}^{2+}+4 \mathrm{H}^{+}\)
Problem 70
What is the correct representation of reaction occurring when \(\mathrm{HCl}\) is heated with \(\mathrm{MnO}_{2} ?\) (a) \(\mathrm{MnO}_{4}^{-}+5 \mathrm{Cl}^{-}+8 \mathrm{H}^{+} \rightarrow \mathrm{Mn}^{2+}+5 \mathrm{Cl}^{-}+5 \mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{MnO}_{2}+2 \mathrm{Cl}^{-}+4 \mathrm{H}^{+} \rightarrow \mathrm{Mn}^{2+}+\mathrm{Cl}_{2}+2 \mathrm{H}_{2} \mathrm{O}\) (c) \(2 \mathrm{MnO}_{2}+4 \mathrm{Cl}^{-}+8 \mathrm{H}^{+} \rightarrow 2 \mathrm{Mn}^{2+}+2 \mathrm{Cl}_{2}+4 \mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{MnO}_{2}+4 \mathrm{HCl} \rightarrow \mathrm{MnCl}_{4}+\mathrm{Cl}_{2}+\mathrm{H}_{2} \mathrm{O}\)
Problem 72
When a manganous salt is fused with a mixture of \(\mathrm{KNO}_{3}\) and solid \(\mathrm{NaOH}\) the oxidation number of \(\mathrm{Mn}\) changes from \(+2\) to (a) \(+4\) (b) \(+3\) (c) \(+6\) (d) \(+7\)
Problem 76
Which of the following acts as a self-indicator? (a) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) (b) \(\mathrm{KMnO}_{4}\) (c) Oxalic acid (d) Iodine
Problem 79
Given below are few statements regarding electrode potentials. Mark the correct statements. (i) The potential associated with each electrode is known as electrode potential. (ii) A negative \(E^{\circ}\) means that the redox couple is a stronger reducing agent than \(\mathrm{H}^{+} / \mathrm{H}_{2}\) couple. (iii) A positive \(E^{\circ}\) means that the redox couple is a weaker reducing agent than \(\mathrm{H}^{+} / \mathrm{H}_{2}\) couple.
Problem 80
What will be the products of electrolysis of an aqueous solution of \(\mathrm{AgNO}_{3}\) with silver electrodes? (a) Ag from Ag anode dissolves while \(\mathrm{Ag}^{+}\)from solution gets deposited on cathode. (b) \(\mathrm{Ag}\) is liberated at cathode and \(\mathrm{O}_{2}\) is liberated at anode. (c) \(\mathrm{Ag}\) at cathode and nitric acid at anode is liberated. (d) No reaction takes place.
Problem 83
Which of the following reactions takes place at anode? (a) Reduction (b) Oxidation (c) Decomposition (d) Dissolution
Problem 84
Which of the following will act as cathode when connected to standard hydrogen electrode which has \(E^{\circ}\) value given as zero? (i) \(Z n^{2+} / Z n, E^{\circ}=-0.76 \mathrm{~V}\) (ii) \(\mathrm{Cu}^{2+} / \mathrm{Cu}, E^{\circ}=+0.34 \mathrm{~V}\) (iii) \(\mathrm{Al}^{3+} / \mathrm{Al}, E^{\circ}=-1.66 \mathrm{~V}\) (iv) \(\mathrm{Hg}^{2+} / \mathrm{Hg}, E^{\circ}=+0.885 \mathrm{~V}\) (a) (i) and (ii) (b) (ii) and (iv) (c) (i) and (iii) (d) (i), (ii), (iii) and (iv)
