Problem 38
What is the oxidation state of \(\mathrm{P}\) in \(\mathrm{Ba}\left(\mathrm{H}_{2} \mathrm{PO}_{2}\right)_{2} ?\) (a) \(+3\) (b) \(+2\) (c) \(+1\) (d) \(-1\)
Problem 39
Which of the following can act as oxidising as well as reducing agent? (a) \(\mathrm{H}_{2} \mathrm{O}_{2}\) (b) \(\mathrm{SO}_{3}\) (c) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{HNO}_{3}\)
Problem 40
When a piece of sodium metal is dropped in water, hydrogen gas evolved because (a) sodium is reduced and acts as an oxidising agent (b) water is oxidised and acts as a reducing agent (c) sodium loses electrons and is oxidised while water in reduced (d) water loses electrons and is oxidised to hydrogen.
Problem 41
In the reaction : \(\mathrm{I}_{2}+2 \mathrm{~S}_{2} \mathrm{O}_{3}^{2-} \rightarrow 2 \mathrm{I}^{-}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}\) (a) \(\mathrm{I}_{2}\) is reducing agent. (b) \(I_{2}\) is oxidising agent and \(\mathrm{S}_{2} \mathrm{O}_{3}^{2-}\) is reducing agent. (c) \(\mathrm{S}_{2} \mathrm{O}_{3}^{2-}\) is oxidising agent. (d) \(\mathrm{I}_{2}\) is reducing agent and \(\mathrm{S}_{2} \mathrm{O}_{3}^{2-}\) is oxidising agent.
Problem 43
Consider the following reaction: \(\mathrm{HCHO}+2\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}+3 \mathrm{OH}^{-} \rightarrow 2 \mathrm{Ag}+\mathrm{HCOO}^{-}\) \(+4 \mathrm{NH}_{3}+2 \mathrm{H}_{2} \mathrm{O}\)
Problem 46
Indicate whether the following conversions represent an oxidation, a reduction or none (neither oxidation \(\begin{aligned}&\text { nor reduction). } \\\&\mathrm{HClO}_{4} & \text { (ii) } \mathrm{NH}_{4}^{+} \text {to } \mathrm{NH}_{3}\end{aligned}\) (i) \(\mathrm{HClO}_{3}\) to \(\mathrm{HClO}_{4}\) (iii) \(\mathrm{NO}_{2}\) to \(\mathrm{N}_{2} \mathrm{O}_{4}\) (iv) \(\mathrm{HSO}_{3}^{-}\)to \(\mathrm{SO}_{4}^{2-}\) (v) \(\mathrm{H}_{2} \mathrm{O}_{2}\) to \(\mathrm{H}_{2} \mathrm{O}\) (i) (ii) (iii) (iv) (v) (a) Oxida- Reduc- None None Oxidation tion tion (b) Oxida- None None Oxida- Reduction tion tion (c) Reduc- Oxida- Reduc- None Reduction tion tion tion (d) Oxida- Reduc- None Reduc- Reduction tion tion tion
Problem 49
Which of the following is true about the given redox reaction? $$ \mathrm{SnCl}_{2}+2 \mathrm{FeCl}_{3} \rightarrow \mathrm{SnCl}_{4}+2 \mathrm{FeCl}_{2} $$ (a) \(\mathrm{SnCl}_{2}\) is oxidised and \(\mathrm{FeCl}_{3}\) acts as oxidising agent. (b) \(\mathrm{FeCl}_{3}\) is oxidised and acts as oxidising agent. (c) \(\mathrm{SnCl}_{2}\) is reduced and acts as oxidising agent. (d) \(\mathrm{FeCl}_{3}\) is oxidised and \(\mathrm{SnCl}_{2}\) acts as a oxidising agent.
Problem 50
Which of the following statements is correct regarding redox reactions? (a) An increase in oxidation number of an element is called reduction. (b) A decrease in oxidation number of an element is called oxidation. (c) A reagent which lowers the oxidation number of an element in a given substance is reductant. (d) A reagent which increases the oxidation number of an element in a given substance is reductant.
Problem 54
Which of the following is a disproportionation reaction? \((c): 2 \mathrm{Fe}_{(6)}+3 \mathrm{H}_{2} \mathrm{O}_{(D} \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3(j)}+3 \mathrm{H}_{2(g)}\) d) \(2 \mathrm{H}_{2} \mathrm{O}_{(\bar{D}}+2 \mathrm{~F}_{2(\mathrm{e})} \rightarrow 4 \mathrm{HF}_{\left(a_{q}\right)}+\mathrm{O}_{2(\mathrm{~g})}\)
Problem 56
Which of the following is not an example of disproportionation reaction? (a) \(4 \mathrm{ClO}_{3}^{-} \rightarrow \mathrm{Cl}^{-}+3 \mathrm{ClO}_{4}^{-}\) (b) \(2 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}\) (c) \(2 \mathrm{NO}_{2}+2 \mathrm{OH}^{-} \rightarrow \mathrm{NO}_{2}^{-}+\mathrm{NO}_{3}^{-}+\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{TiCl}_{4}+2 \mathrm{Mg} \rightarrow \mathrm{Ti}+2 \mathrm{MgCl}_{2}\)
