Question

15. Substance X has a melting point higher than 500°C. It is insoluble both
in water and in organic solvents. It conducts electricity when both solid and
molten. What is X?
A copper B mercury C poly(ethene) D sodium chloride

Answer 1

Answer:

The answer is (a)Copper

Explanation:

Substance X is Copper, which can conduct electricity in both solid and molten states. Its melting point is higher than 500°C and it is insoluble in water and in organic solvents.

• The melting point of Copper is 1085°C.

• While the melting point of NaCl is 801°C, Mercury is -38.9°C, and Polyethylene is 110°C

• Mercury is the only metal that is liquid at standard conditions of temperature and pressure, and it is a fair conductor of electricity.

• In the case of NaCl at the solid-state, ionic compounds have their ions fixed in position, and these ions cannot move. Therefore, solid ionic compounds cannot conduct electricity.

• The Cu metal, on the other hand, conducts electricity in solid as well as in the molten state. In copper, metal-free electrons are present in the outermost shell. Thus, on applying heat, the electrons present in the outermost shell of the metal become mobile and conduct electricity.

• When compared with others, Copper is insoluble in water as well as in organic solvents.

• Polyethylene is a polymer and it is a bad conductor of electricity.