P - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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481.
Trigonal bipyramidal geometry is shown by :
A
$$Xe{O_3}$$
B
$$Xe{O_3}{F_2}$$
C
$$FXeOS{O_2}F$$
D
$${\left[ {Xe{F_8}} \right]^{2 - }}$$
Answer :
$$Xe{O_3}{F_2}$$
The hybridization of $$Xe{O_3}{F_2}$$ is $$s{p^3}d$$ and its structure is trigonal bipyramidal in which oxygen atoms are situated on the plane and the fluoride atoms are on the top and bottom.
482.
Which one of the following oxides of chlorine is obtained by passing dry chlorine over silver chlorate at $${90^ \circ }C?$$
A
$$C{l_2}O$$
B
$$Cl{O_3}$$
C
$$Cl{O_2}$$
D
$$Cl{O_4}$$
Answer :
$$Cl{O_2}$$
Pure $$Cl{O_2}$$ is obtained by passing dry $$C{l_2}$$ over $$AgCl{O_3}$$ at $${90^ \circ }C.$$
\[2AgCl{{O}_{3}}+C{{l}_{2}}\left( \text{dry} \right)\xrightarrow{{{90}^{\circ }}C}\] \[2AgCl+2Cl{{O}_{2}}+{{O}_{2}}\]
483.
Which of the following statements is not valid for oxoacids of phosphorus?
A
Orthophosphoric acid is used in the manufacture of triple superphosphate
B
Hypophosphorous acid is a diprotic acid
C
All oxoacids contain tetrahedral four coordinated phosphorus
D
All oxoacids contain at least one $$P =O$$ unit and one $$P—OH$$ group
Answer :
Hypophosphorous acid is a diprotic acid
Hypophosphorous acid, $${H_3}P{O_2},$$ has the following structure.
As it contains only one replaceable $$H$$-atom ( that is attached with $$O,$$ not with $$P$$ directly ) so it is a monoprotic acid.
All other given statements are true.
484.
Boric acid is the trival name for
A
orthoboric acid
B
metaboric acid
C
pyroboric acid
D
none of these
Answer :
orthoboric acid
No explanation is given for this question. Let's discuss the answer together.
485.
The shape of $$Xe{O_2}{F_2}$$ molecule is
A
trigonal bipyramidal
B
square planar
C
tetrahedral
D
see-saw
Answer :
see-saw
$$Xe{O_2}{F_2}$$ has trigonal bipyramidal geometry, due to
presence of lone pair of electrons on equitorial position, its shape is see-saw.
486.
Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?
A
$$C{l_2} > B{r_2} > {F_2} > {I_2}$$
B
$$B{r_2} > {I_2} > {F_2} > C{l_2}$$
C
$${F_2} > C{l_2} > B{r_2} > {I_2}$$
D
$${I_2} > B{r_2} > C{l_2} > {F_2}$$
Answer :
$$C{l_2} > B{r_2} > {F_2} > {I_2}$$
As the size increases, bond dissociation enthalpy becomes lower. Also, as the size of atoms get smaller, ion pairs on the two atoms get close enough together to experience repulsion. In case of $${F_2},$$ this repulsion is bigger and bond becomes weaker.
Hence, the correct order is $$C{l_2} > B{r_2} > {F_2} > {I_2}.$$
487.
Anhydrous $$AlC{l_3}$$ cannot be obtained from which of the following reactions ?
A
Heating $$AlC{l_3}.6{H_2}O$$
B
By passing dry $$HCl$$ over hot aluminium powder
C
By passing dry $$C{l_2}$$ over hot aluminium powder
D
By passing dry $$C{l_2}$$ over a hot mixture of alumina and coke
Answer :
Heating $$AlC{l_3}.6{H_2}O$$
\[\begin{align}
& 2Al+6HCl\xrightarrow{\Delta ,air}2AlC{{l}_{3}}+3{{H}_{2}} \\
& 2Al+3C{{l}_{2}}\to 2AlC{{l}_{3}} \\
\end{align}\]
\[AlC{{l}_{3}}.6{{H}_{2}}O\xrightarrow{\Delta }Al{{\left( OH \right)}_{3}}+3HCl+3{{H}_{2}}O\]
Thus \[AlC{{l}_{3}}\] cannot be obtained by this method.
488.
Blue liquid which is obtained on reacting equimolar amounts of two gases at $${30^ \circ }C$$ is?
A
$${N_2}O\,$$
B
$${N_2}{O_3}\,$$
C
$${N_2}{O_4}$$
D
$${N_2}{O_5}\,$$
Answer :
$${N_2}{O_3}\,$$
\[NO\left( g \right)+N{{O}_{2}}\left( g \right)\xrightarrow{-{{30}^{\circ }}C}\underset{\left( \text{blue}\,\,\text{liquid} \right)}{\mathop{{{N}_{2}}{{O}_{3}}}}\,\]
489.
Dry $$S{O_2}$$ does not bleach dry flowers because
A
nascent hydrogen responsible for bleaching is produced only in presence of moisture
B
water is the actual reducing agent responsible for bleaching
C
water is stronger acid than $$S{O_2}$$
D
the $$O{H^ - }$$ ions produced by water cause bleaching
Answer :
nascent hydrogen responsible for bleaching is produced only in presence of moisture
$$S{O_2} + 2{H_2}O \to {H_2}S{O_4} + 2\left[ H \right]$$