6
MCQ (Single Correct Answer)
Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?
A
HF
B
HCl
C
HBr
D
HI
7
MCQ (Single Correct Answer)
Bond dissociation enthalpy of $\mathrm{E}-\mathrm{H}$ ( $\mathrm{E}=$ element) bonds is given below. Which of the compounds will act as strongest reducing agent?
| Compound | $\mathrm{NH_3}$ | $\mathrm{PH_3}$ | $\mathrm{AsH_3}$ | $\mathrm{SbH_3}$ |
|---|---|---|---|---|
| $\Delta_{\text {diss }}(E-H) / \mathrm{kJ} \mathrm{mol}^{-1}$ |
389 | 322 | 297 | 255 |
A
$\mathrm{NH_3}$
B
$\mathrm{PH_3}$
C
$\mathrm{AsH_3}$
D
$\mathrm{SbH_3}$
8
MCQ (Single Correct Answer)
On heating with concentrated NaOH solution in an inert atmosphere of $\mathrm{CO}_2$, white phosphorus gives a gas. Which of the following statement is incorrect about the gas?
A
It is highly poisonous and has smell like rotten fish
B
It's solution in water decomposes in the presence of light
C
It is more basic than $\mathrm{NH}_3$
D
It is less basic than $\mathrm{NH}_3$
9
MCQ (Single Correct Answer)
Which of the following acids forms three series of salts?
A
$\mathrm{H}_3 \mathrm{PO}_2$
B
$\mathrm{H}_3 \mathrm{BO}_3$
C
$\mathrm{H}_3 \mathrm{PO}_4$
D
$\mathrm{H}_3 \mathrm{PO}_3$
10
MCQ (Single Correct Answer)
Strong reducing behaviour of $\mathrm{H}_3 \mathrm{PO}_2$ is due to
A
low oxidation state of phosphorus
B
presence of two -OH groups and one $\mathrm{P}-\mathrm{H}$ bond
C
presence of one -OH group and two $\mathrm{P}-\mathrm{H}$ bonds
D
high electron gain enthalpy of phosphorus