23
MCQ (Single Correct Answer)
A black compound of manganese reacts with a halogen acid to give greenish yellow gas. When excess of this gas reacts with $\mathrm{NH}_3$ an unstable trihalide is formed. In this process the oxidation state of nitrogen changes from ............ .
A
$-$3 to +3
B
$-$3 to 0
C
$-$3 to +5
D
0 to $-$3
24
MCQ (Single Correct Answer)
In the preparation of compounds of Xe , Bartlett had taken $\mathrm{O}_2^{+} \mathrm{~Pt~F}_6^{-}$ as a base compound. This is because
A
both $\mathrm{O}_2$ and Xe have same size.
B
both $\mathrm{O}_2$ and Xe have same electron gain enthalpy.
C
both $\mathrm{O}_2$ and Xe have almost same ionisation enthalpy.
D
both Xe and $\mathrm{O}_2$ are gases.
25
MCQ (Single Correct Answer)
In solid state $\mathrm{PCl}_5$ is a ........... .
A
covalent solid
B
octahedral structure
C
ionic solid with $\left[\mathrm{PCl}_6\right]^{+}$octahedral and $\left[\mathrm{PCl}_4\right]^{-}$tetrahedral
D
ionic solid with $\left[\mathrm{PCl}_4\right]^{+}$tetrahedral and $\left[\mathrm{PCl}_6\right]^{-}$octahedral
26
MCQ (Single Correct Answer)
Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidising power.
| Ion | $\mathrm{ CIO_4^-}$ |
$\mathrm{IO_4^-}$` | $\mathrm{BrO_4^-}$ |
|---|---|---|---|
| Reduction potential $E^-/\mathrm{V}$ | $E^o=1.19\mathrm{~V}$ | $E^s=1.65\mathrm{~V}$ | $E^s=1.74\mathrm{~V}$ |
A
$\mathrm{ClO}_4^{-}>\mathrm{IO}_4^{-}>\mathrm{BrO}_4^{-}$
B
$\mathrm{IO}_4^{-}>\mathrm{BrO}_4^{-}>\mathrm{ClO}_4^{-}$
C
$\mathrm{BrO}_4^{-}>\mathrm{IO}_4^{-}>\mathrm{ClO}_4^{-}$
D
$\mathrm{BrO}_4^{-}>\mathrm{ClO}_4^{-}>\mathrm{IO}_4^{-}$
27
MCQ (Single Correct Answer)
Which of the following is isoelectronic pair?
A
$\mathrm{ICl}_2, \mathrm{ClO}_2$
B
$\mathrm{BrO}_2^{-}, \mathrm{BrF}_2^{+}$
C
$\mathrm{ClO}_2, \mathrm{BrF}$
D
$\mathrm{CN}^{-}, \mathrm{O}_3$