Solid State MCQ Questions & Answers in Physical Chemistry | Chemistry
Learn Solid State MCQ questions & answers in Physical Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
31.
Alkali halides do not show Frenkel defect because
A
cations and anions have almost equal size
B
there is a large difference in size of cations and anions
C
cations and anions have low coordination number
D
anions cannot be accommodated in voids
Answer :
cations and anions have almost equal size
Frenkel defect is not shown by alkali metals because cations and anions have almost same size and cations cannot be accommodated in interstitial sites.
32.
Which of the following statements is not true ?
A
Silicon carbide is a covalent crystal.
B
Molecular crystals are soft in nature.
C
In calcium fluoride structure, coordination number of $$C{a^{2 + }}$$ is 4.
D
Increase in radius ratio results in increase in coordination number.
Answer :
In calcium fluoride structure, coordination number of $$C{a^{2 + }}$$ is 4.
Coordination number of $$C{a^{2 + }}$$ in $$Ca{F_2}$$ is 8.
33.
A cubic crystal has
A
thirteen planes of symmetry and nine axis of symmetry.
B
thirteen axis of symmetry and nine planes of symmetry.
C
thirteen axis and thirteen planes of symmetry.
D
nine planes and nine axis of symmetry.
Answer :
thirteen axis of symmetry and nine planes of symmetry.
A cubic crystal possesses a total of 23 elements of symmetry.
Plane of symmetry = ( 3 + 6) = 9
Axes of symmetry = ( 3 + 4 + 6 ) = 13
Centre of symmetry = 1
34.
Which of the following statements is not correct regarding diamond and graphite ?
A
In diamond, each carbon atom is covalently bonded to four other carbon atoms.
B
In graphite, each carbon atom is covalently bonded to three other carbon atoms in the same plane.
C
The $$C-C$$ bond length in graphite isintermediate between single and double bond distances.
D
Diamond is a layered structure, the two layers joined by van der Waals' forces.
Answer :
Diamond is a layered structure, the two layers joined by van der Waals' forces.
Diamond is a rigid three-dimensional network solid resulting in extremely hard structure.
35.
If three elements $$X, Y$$ and $$Z$$ crystallise in a $$ccp$$ lattice with $$X$$ atoms at the corners, $$Y$$ atoms at the cube centre and $$Z$$ atoms at the edges, the formula of the compound will be
A
$$XYZ$$
B
$$XY{Z_2}$$
C
$$XY{Z_3}$$
D
$${X_2}{Y_2}Z$$
Answer :
$$XY{Z_3}$$
No. of $$X$$ atoms $$ = \frac{1}{8} \times 8 = 1$$
No. of $$Y$$ atoms $$= 1$$
No. of $$Z$$ atoms $$ = 12 \times \frac{1}{4} = 3$$
∴ Formula of the compound $$ = XY{Z_3}$$
36.
Which of the following structures is not correctly matched ?
(i) $$NaCl$$ type - $$C{l^ - }\,ions$$ in $$ccp$$ structure.
$$N{a^ + }\,ions$$ in half octahedral holes.
(ii) $$ZnS$$ type - $${S^{2 - }}\,ions$$ in $$ccp$$ structure.
$$Z{n^{2 + }}\,ions$$ in alternate tetrahedral voids.
(iii) $$Ca{F_2}$$ type - $$C{a^{2 + }}\,ions$$ in $$ccp$$ structure.
$${F^ - }\,ions$$ in all tetrahedral voids.
(iv) $$N{a_2}O$$ type - $${O^{2 - }}\,ions$$ in $$ccp$$ structure.
$$N{a^ + }\,ions$$ in all tetrahedral holes.
A
(i)
B
(ii)
C
(iii)
D
(iv)
Answer :
(i)
In $$NaCl$$ type, $$C{l^ - }\,ions$$ form $$ccp$$ structures while $$N{a^ + }\,ions$$ are present in all octahedral voids.
37.
Experimentally it was found that a metal oxide has formula $${M_{0.98}}O.$$ Metal $$M,$$ is present as $${M^{2 + }}$$ and $${M^{3 + }}$$ in its oxide. Fraction of the metal which exists as $${M^{3 + }}$$ would be
A
5.08 %
B
7.01 %
C
4.08 %
D
6.05 %
Answer :
4.08 %
Let the fraction of metal which exists as $${M^{3 + }}$$ be $$x.$$ Then the fraction of metal exists as $${M^{2 + }} = \left( {0.98 - x} \right)$$
$$\eqalign{
& \therefore 3x + 2\left( {0.98 - x} \right) = 2 \cr
& \,\,\,\,\,x + 1.96 = 2 \cr
& \,\,\,\,x = 0.04 \cr
& \therefore \% \,\,{\text{of}}\,\,{M^{3 + }} = \frac{{0.04}}{{0.98}} \times 100 = 4.08\% \cr} $$
38.
In the laboratory, sodium chloride is made by burning sodium in the atmosphere of chlorine. The salt obtained is yellow in colour. The cause of yellow colour is:
A
Presence of $$N{a^ + }\,ions$$ in the crystal lattice
B
Presence of $$C{l^ - }\,ions$$ in the crystal lattice
C
Presence of electrons in the crystal lattice
D
Presence of face centred cubic crystal lattice.
Answer :
Presence of electrons in the crystal lattice
Due to presence of $$F$$ - centres.
39.
A substance $${A_x}{B_y}$$ crystallizes in a face centred cubic $$(FCC)$$ lattice in which atoms $$'A'$$ occupy each corner of the cube and atoms $$'B'$$ occupy the centres of each face of the cube. Identify the correct composition of the substance $${A_x}{B_y}$$
A
$$A{B_3}$$
B
$${A_4}{B_3}$$
C
$${A_3}B$$
D
Compostion cannot be specified
Answer :
$$A{B_3}$$
Effective number of atoms at corners, $$A = 8 \times \frac{1}{8} = 1$$
Effective number of atoms at centre, $$B = \frac{1}{2} \times 6 = 3$$
Thus, the composition will be $$A{B_3}$$
40.
Sodium metal crystallizes in a body centred cubic lattice with a unit cell edge of $$4.29\mathop {\text{A}}\limits^{\text{o}} .$$ The radius of sodium atom is approximately