LATE BABANRAO GABAJI GAWALI CHARITABLE TRUST’S
SPG INTERNATIONAL PUBLIC SCHOOL&JUNIOR COLLEGE
Unit Test-1st (2025-26)
Subject-Chemistry
Class: 12th CBSE Marks: 40
Q.1 Choose Correct Option 10Marks
1. The number of atoms/molecules present in one body centred cubic unit cell is_______
(a) 1 (b) 2 (c) 4 (d) 6
2. Wax is an example of___________
(a) Ionic crystal (b) Covalent crystal (c) Molecular crystal (d) Metallic crystal
3. There are ________ primitive and ________ centered unit cells
(a) 6, 7 (b) 7, 7 (c) 6, 6 (d) 7, 6
4. Which crystal has the largest lattice energy ?
(a) kcl (b) mgo (c) libr (d) naf
5. ABCABC ............. Type predicts _____ structure.
(a) hcp (b) ccp (c) scp (d) none of these
6. In a face centred cubic lattice, a unit cell in shared equally by _______ no. Of unit cells.
(a) 4 (b) 2 (c) 6 (d) 8
7. Which crystal has the largest lattice energy ?
(a) kcl (b) mgo (c) libr (d) naf
8. In a crystal, the atoms are located at the position of ....... Potential energy.
(a) Zero (b) Infinite (c) Minimum (d) Maximum
9. The Bravais lattice where a = b = c, 0 90 is _________.
(a) cubic (b) Rhomboheded (c) Triclinic (d) none of these
10. In a solid lattice the cation has left a lattice site and is located at an interstitial position.
The lattice defect is known as___________
(a) Interstitial defect (b) Valency defect (c) Frenkel defect (d) Schottky defect
Q.2 Answer in One Sentence. 10 Marks
1. Why are solids rigid?
2. Why does table salt, NaCl, sometimes appear yellow in colour?
3. Explain the solubility rule “like dissolves like” in terms of intermolecular forces that exist in
solutions.
4. What is the significance of Henry’s Law constant KH ?
5. What is electrode potential ?
6. How will the pH of brine (NaCl solution) be affected when it is electrolysed?
7. What advantage do the fuel cells have over primary and secondary batteries?
8. State a condition under which a bimolecular reaction is kinetically a first order reaction.
9. Write two characteristic properties of molecular solid.
10. What types of solid are electrical conductors, malleable and ductile ?
Q.3. Match the type of unit cell given in Column I with the features given in Column II.
4Marks
Column I Column II
1.Primitive cubic unit cell a. Each of the three perpendicular edges
compulsorily have a different edge length i.e;
a ≠ b ≠ c.
2. Body-centered cubic unit cell b. Number of atoms per unit cell is one.
3. Face-centered cubic unit cell c. Each of the three perpendicular edges
compulsorily have the same edge length i.e; a
=b=c
4. End-centered orthorhombic unit cell d. The number of atoms present in a unit cell
is two.
e. The number of atoms present in a unit cell
is four
Q.4 Fill in the blanks. 6 Marks
1. In ZnS crystal, Zn2+ ions occupy –––––––.
2. Na2O crystal shows ––––––– structure.
3. Rock salt type structure has ––––––– coordination.
4. In most cubic close-packed lattices, –––––––% of space is filled.
5. Two types of voids are ––––––– and –––––––.
6. Glass is a example of ––––––– solid.
Q.5 Attempt Any Five. 10 Marks
1. What make alkali metal halides sometimes coloured which are otherwise colourless ?
2. What are the structures of NaCl and CsCl ? 6. In which defect the crystal loses its density ?
3. What is packing effeciency of simple cubic crystal ?
4. Amorphous solids are isotropic - explain.
5. What happens when crystalline solids are heated ?
6. What is the significance of henrys law constant KH ?
