Chemical Bonding and Molecular Structure MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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71.
In which of the following pairs the two species are not isostructural?
72.
The number of antibonding electron pairs in $$O_2^{2 - }$$ molecular ion on the basis of molecular orbital theory is $$\left( {{\text{at}}{\text{.}}\,{\text{no}}{\text{.}}\,\,{\text{of}}\,\,{\text{O}}\,\,{\text{is}}\,\,8} \right)$$
A
5
B
2
C
4
D
6
Answer :
4
Total number of electrons in $$O_2^{2 - } = 16 + 2 = 18$$
According to $$MOT,$$ the configuration of $$O_2^{2 - }$$ is
$$\sigma 1{s^2},\mathop \sigma \limits^* 1{s^2},\sigma 2{s^2},\mathop \sigma \limits^* 2{s^2},$$ $$\sigma 2p_x^2,\pi 2p_y^2 \approx \pi 2p_z^2,\mathop \pi \limits^* 2p_y^2 \approx \mathop \pi \limits^ * 2P_z^2$$
So, the number of antibonding electron pairs = 4
73.
How many and what types of bonds are present in $$NH_4^ + ?$$
A
Four covalent bonds
B
Three covalent bonds and one ionic bond
C
Four ionic bonds
D
Three covalent bonds and one coordinate bond
Answer :
Three covalent bonds and one coordinate bond
74.
Which of the following is soluble in water
A
$$C{S_2}$$
B
$$\,{C_2}{H_5}OH$$
C
$$\,CC{l_4}$$
D
$$CHC{l_3}$$
Answer :
$$\,{C_2}{H_5}OH$$
$$\because $$ It forms hydrogen bonds with water
75.
$$B{e^{2 + }}$$ is isoelectronic with which of the following ions?
A
$${H^ + }$$
B
$$L{i^ + }$$
C
$$N{a^ + }$$
D
$$M{g^{2 + }}$$
Answer :
$$L{i^ + }$$
Isoelectronic species contain same number of electrons. $$B{e^{2 + }}$$ contains 2 electrons. Among the given options, only $$L{i^ + }$$ contains 2 electrons and therefore, it is isoelectronic with $$B{e^{2 + }}.$$
$$\eqalign{
& {H^ + } \to {\text{no}}\,{\text{electron}},\,N{a^ + } \to 10{e^ - } \cr
& L{i^ + } \to 2{e^ - } \cr
& M{g^{2 + }} \to 10{e^ - } \cr} $$
Hence, $$B{e^{2 + }}$$ is isoelectronic with $$L{i^ + }.$$
76.
Paramagnetism is shown by the molecules which have
A
paired electrons
B
unpaired electrons
C
lone pair of electrons
D
bond order more than one
Answer :
unpaired electrons
Presence of unpaired electrons makes a molecule paramagnetic. More the number of unpaired electrons, higher is the paramagnetism.
77.
The bond between two identical non-metal atoms has a pair of electrons :
A
unequally shared between the two
B
transferred fully from one atom to another
C
with identical spins
D
equally shared between them
Answer :
equally shared between them
In covalent bonds between two identical non-metal atoms share the pair of electrons equally between them,
e.g. : $${F_2},{O_2},{N_2},$$
78.
The angular shape of ozone molecule $$\left( {{O_3}} \right)$$ consisits of
A
$${\text{1}}\,{\text{sigma}}\,\,{\text{and}}\,\,{\text{2}}\,{\text{pi - bonds}}$$
B
$${\text{2 sigma}}\,\,{\text{and}}\,\,{\text{2}}\,{\text{pi - bonds}}$$
C
$${\text{1}}\,{\text{sigma}}\,\,{\text{and}}\,\,{\text{1}}\,{\text{pi - bonds}}$$
D
$${\text{2}}\,{\text{sigma}}\,\,{\text{and}}\,\,{\text{1}}\,{\text{pi - bonds}}$$
In case of single bond, there is only one $$\sigma - {\text{bond}},$$ in case of double bond, there is one $$\sigma $$ and one $$\pi - {\text{bonds}}$$ while in case of triple bond, there is one $$\sigma $$ and two $$\pi - {\text{bonds}}{\text{.}}$$ Thus, angular shape of ozone $$\left( {{O_3}} \right)$$ contains $${\text{2}}\sigma $$ and $$1\pi - {\text{bonds}}$$ as shown below
79.
$$KF$$ combines with $$HF$$ to form $$KH{F_2}.$$ The compound contains the species
A
$${K^ + },{F^ - }\,{\text{and}}\,{H^ + }$$
B
$${K^ + },{F^ - }\,{\text{and}}\,HF$$
C
$${K^ + }\,{\text{and}}\,{\left[ {H{F_2}} \right]^ - }$$
D
$${\left[ {KHF} \right]^ + }{\text{and}}\,{F_2}$$