141. 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
$$2{S_2}O_3^{2 - } \to {S_4}O_6^{2 - }$$
Answer :
$$CrO_4^{2 - } \to C{r_2}O_7^{2 - }$$
142.
Which of the following is correct code for $$x$$ and $$y$$ in the following reaction.
(i) $$x =$$ oxidation reaction, $$y =$$ reduction reaction
(ii) $$x =$$ gain of two electrons, $$y =$$ loss of two electrons,
(iii) $$x =$$ reduction reaction, $$y =$$ oxidation reaction
(iv) $$x =$$ loss of two electrons, $$y =$$ gain of two electrons
A
(i) and (ii)
B
(i) and (iv)
C
(ii) and (iii)
D
(iii) and (iv)
Answer :
(i) and (iv)
143. Phosphorus on reaction with $$NaOH$$ products $$P{H_3}$$ and $$Na{H_2}P{O_2}.$$ This reaction is an example of
A
oxidation
B
reduction
C
disproportionation
D
displacement
Answer :
disproportionation
144. Which of the following statements is not correct?
A
The oxidation number of $$S$$ in $${\left( {N{H_4}} \right)_2}{S_2}{O_8}$$ is $$+6.$$
B
The oxidation number of $$Os$$ in $$Os{O_4}$$ is $$+8.$$
C
The oxidation number of $$S$$ in $${H_2}S{O_5}$$ is $$+8.$$
D
The oxidation number of $$O$$ in $$K{O_2}$$ is $$ - \frac{1}{2}.$$
Answer :
The oxidation number of $$S$$ in $${H_2}S{O_5}$$ is $$+8.$$
145.
The values of coefficients to balance the following reaction are $$Cr{\left( {OH} \right)_3} + Cl{O^ - } + O{H^ - } \to $$ $$CrO_4^{2 - } + C{l^ - } + {H_2}O$$
| $$Cr{\left( {OH} \right)_3}$$ | $$Cl{O^ - }$$ | $$CrO_4^{2 - }$$ | $$C{l^ - }$$ | |
| (a) | 2 | 3 | 3 | 3 |
| (b) | 2 | 4 | 3 | 2 |
| (c) | 2 | 4 | 4 | 2 |
| (d) | 2 | 3 | 2 | 3 |
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(d)
146. What is the oxidation state of $$P$$ in $$Ba{\left( {{H_2}P{O_2}} \right)_2}?$$
A
+ 3
B
+ 2
C
+ 1
D
- 1
Answer :
+ 1
147.
Based on the following reactions, arrange the metals in increasing order of their reduction potentials.
$$Zn + C{u^{2 + }} \to Z{n^{2 + }} + Cu;$$ $$Mg + Z{n^{2 + }} \to M{g^{2 + }} + Zn;$$ $$Cu + 2A{g^ + } \to C{u^{2 + }} + 2Ag$$
A
$$Mg > Zn > Cu > Ag$$
B
$$Mg < Zn < Cu < Ag$$
C
$$Zn < Cu < Ag < Mg$$
D
$$Mg > Cu > Zn > Ag$$
Answer :
$$Mg < Zn < Cu < Ag$$
148. Oxidation number of iodine in $$IO_3^ - ,IO_4^ - ,KI$$ and $${I_2}$$ respectively is
A
-2, -5, -1, 0
B
+5, +7, -1, 0
C
+2, +5, +1, 0
D
-1, +1, 0, +1
Answer :
+5, +7, -1, 0
149. The oxidation number of $$S$$ in $$N{a_2}{S_4}{O_6}$$ is
A
+0.5
B
2.5
C
+4
D
+6
Answer :
2.5
150. One gas bleaches the colour of flowers by reduction, while the other by oxidation
A
$$CO\,{\text{and}}\,C{l_2}$$
B
$$S{O_2}\,{\text{and}}\,C{l_2}$$
C
$${H_2}S\,{\text{and}}\,B{r_2}$$
D
$$N{H_3}\,{\text{and}}\,S{O_2}$$
Answer :
$$S{O_2}\,{\text{and}}\,C{l_2}$$