1. Solid-state is denser than the liquid and gaseous states of the same substance. Which of the following is an exception to this rule?
a) Mercury
b) Carbon dioxide (dry ice)
c) Ice
d) NaCl
Explanation: The density of ice is about 0.92 g/cm3 while that of water is 1 g/cm3. Mercury has density 14.184 g/cm3 as solid and 13.69 g/cm3 as liquid. Carbon dioxide has density 1.56 g/cm3 as solid and 1.10 g/cm3 as liquid. NaCl has density 2.71 g/cm3 as solid and 1.556 g/cm3 in molten state. Therefore only ice has lesser density as a solid than as a liquid.
2. Which of the following can be used to describe a crystalline solid?
a) Heterogeneous, anisotropic
b) Homogeneous, anisotropic
c) Heterogeneous, isotropic
d) Homogeneous, isotropic
Explanation: Homogeneity refers to uniformity in composition, which is a characteristic property of crystalline solids. Isotropy is when the values of physical properties do not change with direction throughout the body of the solid. Crystalline solids are anisotropic because the composition of the solid changes with direction, hence the physical properties also change with direction.
3. When a single substance can crystallize in two or more forms under different conditions provided, it is called as _________
a) Polymorphous
b) Isomorphous
c) Semimorphous
d) Multimorphous
Explanation: Isomorphous is when two or more substances have the same crystal structure. Polymorphous is when a single substance can crystallize in two or more forms depending upon the conditions.
4. Which of the following is an amorphous solid?
a) Quartz
b) Quartz glass
c) Graphite
d) Salt (NaCl)
Explanation: Quartz glass does not have a perfectly ordered structure, hence it is classified as an amorphous solid. The rest are crystalline solids due to ordered structures.
5. Amorphous solids are actually supercooled liquids.
a) True
b) False
Explanation: Amorphous solids behave like fluids and flow very slowly under the influence of gravity. Hence, they are said to be supercooled liquids.
6. Which type of solid structure melts at a definite, sharp melting point?
a) All types of solids
b) No type of solid
c) Amorphous solids
d) Crystalline solids
Explanation: Crystalline solids have a perfectly ordered structure which collapses immediately at a specific temperature. Amorphous solids melt over a range of temperatures, not one specific value.
7. Which of the following describes a general solid?
a) Compressible
b) Incompressible
c) Fluid
d) Semi-compressible
Explanation: The intermolecular forces of attraction in a solid are very strong, making it incompressible. Gases are highly compressible, while liquids are semi-compressible. Fluid is a property of a substance that can ‘flow’.
8. _________ is the basic repeated structural unit of a crystalline solid.
a) Monomer
b) Molecule
c) Unit cell
d) Atom
Explanation: Crystalline solids are composed of many small crystals, each of which is called a unit cell. It is a specific term. Monomer is the basic unit for a polymer, and atoms make up molecules, which can further arrange themselves to form solids, liquids or gases.
9. Which of the following statements is true for an amorphous solid?
a) Long range order is present
b) Short range order is present
c) There is no orderly arrangement
d) Complete order is present at lower temperatures
Explanation: For an amorphous solid there is short range order present which is independent of the temperature. Long range order is present in crystalline solids.
10. Sulfur exists in two polymorphic forms ____________ and ______________
a) rhombic and monoclinic
b) rhombic and triclinic
c) hexagonal and triclinic
d) hexagonal and monoclinic
Explanation: There are two polymorphous structures of sulfur, rhombic and monoclinic. Polymorphous structures occur when a single substance can crystallize in two or more forms depending upon the conditions.
