1. In polar molecular solids, the molecules are held together by ________
a) dipole-dipole interactions
b) dispersion forces
c) hydrogen bonds
d) covalent bonds
Explanation: Molecular solids are solids that are collections of molecules held together by intermolecular forces. In polar molecules such as HCl, So2, etc., the molecules are held together by dipole-dipole interactions.
2. Diamond is an example of _______
a) solid with hydrogen bonding
b) electrovalent solid
c) covalent solid
d) glass
Explanation: The solids in which constituent particles are attached to each other by covalent bonds are called covalent solids. Diamond, graphite, silicon, SiC, AIN, quartz are examples of covalent solids.
3. Silicon is found in nature in the forms of ________
a) body-centered cubic structure
b) hexagonal-closed packed structure
c) network solid
d) face-centered cubic structure
Explanation: Silicon due to its catenation property form network solid. Catenation is the ability of an atom to form bonds with other atoms of the same element. The compounds of silicon are reactive and not stable.
4. Which one of the following are the dimensions of cubic crystal?
a) a =b ≠ c
b) a = b = c and α = β ≠ γ = 90
c) a = b = c and α = β = γ = 90
d) a ≠ b = c and α = β ≠ γ = 90
Explanation: The dimensions of a cubic crystals are a = b = c, α = β = γ = 90.
5. Which of the following is not a crystal system?
a) Cubic
b) Trigonal
c) Triclinic
d) Hexaclinic
Explanation: Hexaclinic is not a crystal system. Their crystal system are cubic, tetragonal, rhombohedral or trigonal, orthorhombic or rhombic, monoclinic, triclinic and hexagonal.
6. In face-centred cubic cell, a unit cell is shared equally by __________
a) four unit cells
b) two unit cells
c) one unit cell
d) six unit cells
Explanation: The unit cell in which atoms are present at corners as well as faces of unit cell is known as face-centred cubic unit cell. In face-centred cubic cell, a unit cell is shared equally by six unit cells.
7. The unit cell with a≠b≠c and α=β=γ=90 refers to __________ crystal system.
a) hexagonal
b) trigonal
c) triclinic
d) orthorhombic
Explanation: In orthorhombic crystal system, all three axes are unequal in length and all are perpendicular to one another. It is also called as rhombic crystal system. Topaz, barite are some examples of orthorhombic crystals.
8. Which is the most unsymmetrical crystal system?
a) Triclinic crystal system
b) Cubic crystal system
c) Hexagonal crystal system
d) Trigonal crystal system
Explanation: Most unsymmetrical crystal system is triclinic in which all three axes are unequal in length none is perpendicular to another. Triclinic unit cells has the least symmetrical shape of all unit cells. Turquoise is an example of triclinic crystal.
9. In the simple cubic cell, each corner atom is shared by __________
a) eight unit cells
b) one unit cell
c) two unit cells
d) six unit cells
Explanation: The unit cell in which the constituent atoms are present only at the corner is known as simple cubic cell. It is also referred to as a primitive cubic cell. In the simple cubic cell, each corner atom is shared by eight different unit cells.
10. The points which shows the position of atoms in crystal are called as _________
a) crystal lattice
b) crystal parameters
c) bravais lattice
d) lattice point
Explanation: The point at which the atoms may be present on the unit cell is termed as lattice point. It shows the position of atoms in crystal.
