Assertion : Crystals of hydrated calcium sulphate $\left(\mathrm{gypsum} : {\mathrm{CaSO}}_4, 2{\mathrm{H}}_2\mathrm{O}\right)$ are soft and easily cleaved.

Reason : Crystals of anhydrous calcium sulphate $\left(\mathrm{anhydrite} : {\mathrm{CaSO}}_4\right)$ are very hard and very difficult

               to cleave.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

 When two atoms combine to form a molecule, energy is: 

A compound having the Highest Melting Point :

1. BeCl₂

2. MgCl₂

3. CaCl₂

4. SrCl₂

The diamagnetic species among the following is:

1. NO

2. CO

3. O₂

4. B₂

Which of the statements are not true for AlCl₃-

1. AlCl₃ fumes in moist air forms HCl with moisture

2. Anhydrous AlCl₃ exists as Al₂Cl₆

3. Anhydrous AlCl₃ is ionic

4. Anhydrous AlCl₃ is trigonal planar molecule at higher temperature

Valency is best described as:

1. Total electrons in an atom

2. Atomicity of an element

3. Oxidation number of an element

4. Combining capacity of an element

Compounds that have a maximum value of lattice energy among the following, is:
 

A Compound with maximum ionic character is formed from:

The crystal lattice of electrovalent compound is composed of :

1. Atoms

2. Molecules

3. Oppositely charged ions

4. Both molecules and ions

Ions are formed from neutral atoms by-

1. Loss of electrons

2. Gain of electrons

3. Sharing of electrons

4. Loss and gain of electrons