21. When X-ray diffraction pattern consists of sharply defined rings, the solid is
(a) Monocrystalline
(b) Amorphous
(c) Polycrystalline
(d) None of these

Answer: (c)

22. The number of atoms per unit cell in a simple cubic, FCC and BCC unit cells is, respectively
(a) 2, 1 and 4
(b) 1, 4 and 2
(c) 2, 4 and 1
(d) 1, 2 and 4

Answer: (b)

23. No Bragg reflection of X-rays from a crystal will be observed if 

 is smaller than
(a) 𝜆/4
(b) 𝜆/3
(c) 𝜆/2
(d) 𝜆

Answer: (c)

24. CaO and NaCl have similar crystal structures and approximately same ionic radii. If U is the lattice energy of NaCl, the lattice energy of CaO is nearly
(a) 0.5𝑈
(b) 𝑈
(c) 2𝑈
(d) 4𝑈

Answer: (d)

25. For which of the following process is inter system crossing (ISC) essential?
(a) Chemiluminescence
(b) Fluorescence
(c) Phosphorescence
(d) Radioactive decays

Answer: (c)

26. Which of the following set of quantum numbers are possible?
1. 𝑛 = 3, 𝑙 = 0, 𝑚 = 0 and 𝑠 =+1/2
2. 𝑛 = 3, 𝑙 = 1, 𝑚 = −1 and 𝑠 = −1/2
3. 𝑛 = 2, 𝑙 = 0, 𝑚 = −1 and 𝑠 = +1/2
4. 𝑛 = 2, 𝑙 = 1, 𝑚 = 0 and 𝑠 = +1/2

(a) 1, 2 and 3
(b) 1, 3 and 4
(c) 1, 2 and 4
(d) 2, 3 and 4

Answer: (c)

27. The pH , at which the amino acid is in the dipolar form is known as:
(a) Isoelectric point
(b) Isosbestic point
(c) Mutarotation
(d) Transition point

Answer: (a)

28. The following two isomers are:
(a) Enantiomers
(b) Mesomers
(c) Diastereomers
(d) Position isomers

Answer: (c)

29. Consider the following compounds:
Which of the above two compounds exhibit functional group isomerism?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 4

Answer: (a)

30. Consider the following about propane:
1. Bond angle is 109.5°
2. Each carbon is 𝑠𝑠𝑠 3 hybridized
3. It is combustible
4. It can be polymerized

Which of the above statements are correct?
(a) 1, 2 and 4
(b) 1, 3 and 4
(c) 2, 3 and 4
(d) 1, 2 and 3

Answer: (d)