6
MCQ (Single Correct Answer)
The oxidation number of an element in a compound is evaluated on the basis of certain rules. Which of the following is incorrect in this respect?
A
The oxidation number of hydrogen is always +1
B
The algebraic sum of all the oxidation numbers in a compound is zero
C
An element in the free or the uncombined state bears oxidation number zero
D
In all its compounds, the oxidation number of fluorine is $-$1
7
MCQ (Single Correct Answer)
In which of the following compounds, an element exhibits two different oxidation states?
A
$\mathrm{NH}_2 \mathrm{OH}$
B
$\mathrm{NH}_4 \mathrm{NO}_3$
C
$\mathrm{N}_2 \mathrm{H}_4$
D
$\mathrm{N}_3 \mathrm{H}$
8
MCQ (Single Correct Answer)
Which of the following arrangements represent increasing oxidation number of the central atom?
A
$\mathrm{CrO}_2^{-}, \mathrm{ClO}_3^{-}, \mathrm{CrO}_4^{2-}, \mathrm{MnO}_4^{-}$
B
$\mathrm{ClO}_3^{-}, \mathrm{CrO}_4^{2-}, \mathrm{MnO}_4^{-}, \mathrm{CrO}_2^{-}$
C
$\mathrm{CrO}_2^{-}, \mathrm{ClO}_3^{-}, \mathrm{MnO}_4^{-}, \mathrm{CrO}_4^{2-}$
D
$\mathrm{CrO}_4^{2-}, \mathrm{MnO}_4^{-}, \mathrm{CrO}_2^{-}, \mathrm{ClO}_3^{-}$
9
MCQ (Single Correct Answer)
The largest oxidation number exhibited by an element depends on its outer electronic configuration. With which of the following outer electronic configurations the element will exhibit largest oxidation number?
A
$3 d^1 4 s^2$
B
$3 d^3 4 s^2$
C
$3 d^5 4 s^1$
D
$3 d^5 4 s^2$
10
MCQ (Single Correct Answer)
Identify disproportionation reaction
A
$\mathrm{CH}_4+2 \mathrm{O}_2 \longrightarrow \mathrm{CO}_2+2 \mathrm{H}_2 \mathrm{O}$
B
$\mathrm{CH}_4+4 \mathrm{Cl}_2 \longrightarrow \mathrm{CCl}_4+4 \mathrm{HCl}$
C
$2 \mathrm{~F}_2+2 \mathrm{OH}^{-} \longrightarrow 2 \mathrm{~F}^{-}+\mathrm{OF}_2+\mathrm{H}_2 \mathrm{O}$
D
$2 \mathrm{NO}_2+2 \mathrm{OH}^{-} \longrightarrow \mathrm{NO}_2^{-}+\mathrm{NO}_3^{-}+\mathrm{H}_2 \mathrm{O}$