Question

Which of the following act as reducing agents ?
$$\eqalign{ & {\text{(i)}}\,PO_4^{3 - } \cr & {\text{(ii)}}\,S{O_3} \cr & {\text{(iii)}}\,PO_3^{2 - } \cr & {\text{(iv)}}\,N{H_3} \cr} $$

A. (i), (ii) and (iii)
B. Only (iii)
C. (i), (iii) and (iv)
D. (iii) and (iv)  
Answer :   (iii) and (iv)
Solution :
In (i) and (ii) both $$P$$ and $$S$$ are in highest oxidation state. In (iii) and (iv) ; $$P$$ has oxidation state of $$+4$$  which can be oxidized to $$+5$$  state, while in case of $$N{H_3}$$  nitrogen has oxidation state of $$–3$$  which can be oxidised.

Releted MCQ Question on
Physical Chemistry >> Redox Reaction

Releted Question 1

Which of the following represents a redox reaction?

A. $$NaOH + HCl \to NaCl + {H_2}O$$
B. $$BaC{l_2} + {H_2}S{O_4} \to BaS{O_4} + 2HCl$$
C. $$CuS{O_4} + 2{H_2}O \to Cu{\left( {OH} \right)_2} + {H_2}S{O_4}$$
D. $$Zn + 2HCl \to ZnC{l_2} + {H_2}$$
Releted Question 2

Which reaction involves neither oxidation nor reduction?

A. $$CrO_4^{2 - } \to C{r_2}O_7^{2 - }$$
B. $$Cr \to CrC{l_3}$$
C. $$Na \to N{a^ + }$$
D. $$2{S_2}O_3^{2 - } \to {S_4}O_6^{2 - }$$
Releted Question 3

$$Zn$$  gives $${H_2}$$  gas with $${H_2}S{O_4}$$  and $$HCl$$  but not with $$HN{O_3}$$  because

A. Zn acts as an oxidising agent when it reacts with $$HN{O_3}$$
B. $$HN{O_3}$$  is weaker acid than $${H_2}S{O_4}$$  and $$HCl$$
C. In electrochemical series, $$Zn$$  is above hydrogen
D. $$NO_3^ - $$  is reduced in preference to hydronium $$ion$$
Releted Question 4

A compound of $$Xe$$  and $$F$$  is found to have $$53.5\% $$  of $$Xe.$$  What is oxidation number of $$Xe$$  in this compound ?

A. $$-4$$
B. $$0$$
C. $$+4$$
D. $$+6$$

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Redox Reaction


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