Problem 2
Which of the following is not a redox reaction? (a) \(\mathrm{CuO}+\mathrm{H}_{2} \rightarrow \mathrm{Cu}+\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{Na}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NaOH}+\frac{1}{2} \mathrm{H}_{2}\) (c) \(\mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}+\mathrm{CO}_{2}\) (d) \(2 \mathrm{~K}+\mathrm{F}_{2} \rightarrow 2 \mathrm{KF}\)
Problem 3
Which species is acting as a reducing agent in the following reaction? \(14 \mathrm{H}^{*}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+3 \mathrm{Ni} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}+3 \mathrm{Ni}^{2 *}\) (a) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\) (b) Ni (c) \(\mathrm{H}^{*}\) (d) \(\mathrm{H}_{2} \mathrm{O}\)
Problem 6
Which of the following is not a rule for calculating oxidation number? (a) For ions, oxidation number is equal to the charge on the ion. (b) The oxidation number of oxygen is \(-2\) in all of its compounds. (c) The oxidation number of fluorine is \(-1\) in all of its compounds. (d) Oxidation number of hydrogen is \(+1\) except in binary hydrides of alkali metals and alkaline earth metals where it is \(-1\).
Problem 8
Oxidation state of iron in \(\mathrm{Fe}(\mathrm{CO})_{4}\) is (a) \(+1\) (b) \(-1\) (c) \(+2\) (d) 0
Problem 10
Oxidation numbers of \(\mathrm{Mn}\) in its compounds \(\mathrm{MnCl}_{2}\) \(\mathrm{Mn}(\mathrm{OH})_{3}, \mathrm{MnO}_{2}\) and \(\mathrm{KMnO}_{4}\) respectively are (a) \(+2,+4,+7,+3\) (b) \(+2,+3,+4,+7\) (c) \(+7,+3,+2,+4\) (d) \(+7,+4,+3,+2\)
Problem 11
Arrange the oxides of nitrogen in increasing order of oxidation state of \(\mathrm{N}\) from \(+1\) to \(+5\). $$ \begin{aligned} &\mathrm{N}_{2} \mathrm{O}<\mathrm{N}_{2} \mathrm{O}_{3}<\mathrm{NO}_{2}<\mathrm{N}_{2} \mathrm{O}_{5}\\\ &\begin{aligned} &\text { (a) } \mathrm{N}_{2} \mathrm{O}<\mathrm{NO}<\mathrm{N}_{2} \mathrm{O}_{3}<\mathrm{NO}_{2}<\mathrm{N}_{2} \mathrm{O}_{5} \\ &\text { (b) } \mathrm{N}_{2} \mathrm{O}<\mathrm{NO}_{2}<\mathrm{N}_{2} \mathrm{O}_{3}<\mathrm{NO}<\mathrm{N}_{2} \mathrm{O} \\ &\text { (c) } \mathrm{N}_{2} \mathrm{O}_{5}<\mathrm{N}_{2} \mathrm{O}<\mathrm{NO}_{2}<\mathrm{N}_{2} \mathrm{O}_{3}<\mathrm{N}_{2} \mathrm{O}_{5} \end{aligned} \end{aligned} $$
Problem 14
Which of the following species has an atom with \(+6\) oxidation state? (a) \(\mathrm{MnO}_{4}^{-}\) (b) \(\mathrm{Cr}(\mathrm{CN})_{6}^{3-}\) (c) \(\mathrm{NiF}_{6}^{2-}\) (d) \(\mathrm{CrO}_{2} \mathrm{Cl}_{2}\)
Problem 16
The element that does not show positive oxidation state is (a) \(\mathrm{O}\) (b) \(\mathrm{N}\) (c) \(\mathrm{Cl}\) (d) \(\mathrm{F}\)
Problem 17
Oxidation number of iodine in \(\mathrm{IO}_{3}^{-}, 1 \mathrm{O}_{4}^{-}, \mathrm{Kl}\) and \(\mathrm{I}_{2}\) respectively is (a) \(-2,-5,-1,0\) (b) \(+5,+7,-1,0\) (c) \(+2,+5,+1,0\) (d) \(-1,+1,0,+1\)
Problem 18
Various oxidation states of few elements are mentioned. Which of the options is not correctly matched? (a) Phosphorus: \(+3\) to \(+5\) (b) Nitrogen: \(+1\) to \(+5\) (c) lodine: \(-1\) to \(+7\) (d) Chromium : \(-3\) to \(+6\)
