A solid crystal of NH3 is Question 24 options: soft, low melting, a poor electrical conductor. soft, low melting, a good electrical conductor. hard, high melting, a good electrical conductor. hard, high melting, a poor electrical conductor. soft, high melting, a poor electrical conductor.

soft, low melting , a poor electrical conductor

Explanation:

In a solid crystal of NH3; there exist a covalent bonding in between the Nitrogen and the hydrogen atoms. Thus the NH3 solid crystal is soft due as a result of covalent bonding. Covalent bonds are formed between two or more atoms having zero or very small electronegativity difference.

However in a covalent bond, a low temperature of heat is sufficient in melting  solid crystals of NH3.

SImilarly,in NH3 , the crystal structures , the crystal lattice of NH3 are fixed . Hence , the remain a poor conductor of electricity as they partially dissociate into ions in water.

Thus; A solid crystal of NH3 is soft,have a  low melting and a poor electrical conductor.

the answer to this question is 3.