Week 3

Valency is defined as the number of electrons that must be:

• Gained by an atom to obtain stable configuration

• Lost by an atom to obtain a stable configuration

• Gain or lost by an atom to obtain a stable configuration

• It determines the number of bonds that can be formed with other atoms

Which amongst the following is the correct order of the strength of bonds, in general?

• lonic > Covalent > Vanderwall interaction > Hydrogen

• Hydrogen lonic bond > Covalent > Vanderwall interaction

• Hydrogen Covalent > Ionic > Vanderwall interaction

• Ionic Covalent > Hydrogen > Vanderwall interaction

Which type of bonds are directional and non-directional in nature, respectively?

• Ionic and Covalent

• Covalent and Ionic

• Vander wall and lonic

• Vander wall and Metallic

State true or false: The Vander wall bonds greatly influence material properties such as viscosity and surface tension.

• True

• False

The figure below shows the relation between the interatomic particle distance and lattice energy of two different materials: Material A and B. Select the correct option from the following.

• The coefficient of thermal expansion of Material A and B is the same

• The coefficient of thermal expansion of Material A is higher than that of Material B

• Material A has a higher modulus compared to material B

• Material B has a higher modulus compared to material A

State which one of the following statements are correct regarding transgranular and intergranular cracks?

• Transgranular cracks take place in materials where grain boundaries have low toughness.

• Intergranular cracks take place in the material where grain boundaries have low toughness.

• Transgranular cracks take place in materials where grain boundaries have high toughness.

• Intergranular cracks take place in the material where grain boundaries have high toughness.

Out of the following statements related to the properties of crystals, which is/are true?

• The cooling rate of the material governs the size of the grains

• FCC space lattice has a total of four atoms per unit cell and eight as coordination number

• BCC space lattice has a total of two atoms per unit cell and eight as coordination number

• Every material will try to reach a maximum energy state for stability.

Figure given below shows the phase diagram of water. Select the appropriate option showing the transition between the phases.

• A-Deposition, B-Melting, C-Condensation, D-Freezing

• A-Sublimation, B-Condensation, C- Vaporization, D - Melting

• A-Deposition, B-Condensation, C- Vaporization, D-Freezing

• A-Freezing, B-Condensation, C-Vaporization, D - Melting

Match the following:

• A-ii & iii, B- iv, C-i

• A-iv, B-ii, C-iii

• A-iii, B-iv, C-iii

• A-ii & iii, Biii, C-i