P - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
Learn P - Block Elements MCQ questions & answers in Inorganic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
171.
Which one has the lowest boiling point?
A
$$N{H_3}$$
B
$$P{H_3}$$
C
$$AsC{l_3}$$
D
$$Sb{H_3}$$
Answer :
$$P{H_3}$$
In the hydrides of group 15, the boiling points changes as
$$\mathop {N{H_3}}\limits_{238.5\,K} > \mathop {P{H_3}}\limits_{185.5K} < \mathop {As{H_3}}\limits_{210.6K} < \mathop {Sb{H_3}}\limits_{254.6K} < \mathop {Bi{H_3}}\limits_{290K} $$
∴ Generally mass increases then boiling point increases.
The higher boiling point of $${N{H_3}}$$ is due to excessive hydrogen bonding, so $${P{H_3}}$$ have lowest boiling point among hydrides of group number 15, i.e. nitrogen family.
172.
What are the products formed when chlorine is passed through aqueous hypo solution?
173.
The comparatively high boiling point of hydrogen fluoride is due to
A
high reactivity of fluorine
B
small size of hydrogen atom
C
formation of hydrogen bonds
D
small size of fluorine
Answer :
formation of hydrogen bonds
$$HF$$ molecules are associated through $$H$$ - bonds.
174.
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
$$HI$$
Answer :
$$HF$$
No explanation is given for this question. Let's discuss the answer together.
175.
What may be expected to happen when phosphine gas is mixed with chlorine gas?
A
$$PC{l_3}\,{\text{and}}\,HCl$$ are formed and the mixture warms up
B
$$PC{l_5}\,{\text{and}}\,HCl$$ are formed and the mixture cools down
C
$$P{H_3}.\,C{l_2}$$ is formed with warming up
D
The mixture only cools down
Answer :
The mixture only cools down
On mixing phosphine with chlorine gas $$PC{l_5}\,{\text{and}}\,HCl$$ : forms.The mixture cools down.
$$P{H_3} + 4\,C{l_2} \to PC{l_5} + 3HCl$$
176.
Sulphur molecule is
A
diatomic
B
triatomic
C
tetratomic
D
octa-atomic.
Answer :
octa-atomic.
Sulphur is $${S_8}$$ molecule hence it is octa-atomic.
177.
Buckminsterfullerene is
A
graphite
B
diamond
C
$$C$$ - 60
D
quartz
Answer :
$$C$$ - 60
No explanation is given for this question. Let's discuss the answer together.
178.
Of the following chemical equations :
$$\eqalign{
& P + 3LiAl{H_4} \to X + 3LiF + 3Al{F_3} \cr
& X + 6{H_2}O \to Y + 6{H_2} \cr
& 3X + 3{O_2}\buildrel \Delta \over
\longrightarrow {B_2}{O_3} + 3{H_2}O \cr} $$
$$P, X$$ and $$Y$$ respectively are
A
$$N{a_2}{B_4}{O_7},{H_3}B{O_3},{B_2}{O_3}$$
B
$${H_3}B{O_3},{B_2}{H_6},B{F_3}$$
C
$$B{F_3},{B_2}{H_6},{H_3}B{O_3}$$
D
$${H_3}B{O_3},N{a_2}{B_4}{O_7},{B_2}{O_3}$$
Answer :
$$B{F_3},{B_2}{H_6},{H_3}B{O_3}$$
$$\mathop {4B{F_3}}\limits_{\left( P \right)} + 3LiAl{H_4} \to $$ $$\mathop {2{B_2}{H_6}}\limits_{\left( X \right)} + 3Al{F_3} + 3LiF$$
$$\eqalign{
& \mathop {{B_2}{H_6}}\limits_{\left( X \right)} + 6{H_2}O \to \mathop {2{H_3}B{O_3}}\limits_{\left( Y \right)} + 6{H_2} \cr
& \mathop {{B_2}{H_6}}\limits_{\left( X \right)} + 3{O_2} \to {B_2}{O_3} + 3{H_2}O \cr} $$
179.
Excess of $$KI$$ reacts with $$CuS{O_4}$$ solution and then $$N{a_2}{S_2}{O_3}$$ solution is added to it. Which of the statements is incorrect for this reaction ?
A
$$N{a_2}{S_2}{O_3}$$ is oxidised
B
$$Cu{I_2}$$ is formed
C
$$C{u_2}{I_2}$$ is formed
D
Evolved $${I_2}$$ is reduced
Answer :
$$Cu{I_2}$$ is formed
\[\begin{align}
& 4\overset{-1}{\mathop{KI}}\,+2CuS{{O}_{4}}\to \overset{0}{\mathop{{{I}_{2}}}}\,+C{{u}_{2}}{{I}_{2}}+2{{K}_{2}}S{{O}_{4}} \\
& \overset{0}{\mathop{{{I}_{2}}}}\,+2N{{a}_{2}}\overset{2+}{\mathop{{{S}_{2}}}}\,{{O}_{3}}\to N{{a}_{2}}\overset{+2.5}{\mathop{{{S}_{4}}}}\,{{O}_{6}}+2\overset{-1}{\mathop{NaI}}\, \\
& \text{In this }Cu{{I}_{2}},\text{is not formed}\text{.} \\
\end{align}\]
180.
Among the following which is the strongest oxidising agent?
A
$${F_2}$$
B
$$B{r_2}$$
C
$${I_2}$$
D
$$C{l_2}$$
Answer :
$${F_2}$$
Fluorine is the most electronegative element because electronegativity decreases on moving down the group. Hence, it gets reduced readily into $${F^ - }$$ $$ion$$ and is the strongest oxidising agent. NOTE
The electron gain enthalpy of fluorine is less negative than that of chlorine inspite of that flourine is the strongest oxidising agent. This is due to its low bond dissociation energy and high heat of hydration as compared to those of chlorine.