Which of the following is an example of a nonmetallic mineral?
a. sulfur
b. lead
c. aluminum
d. gold

Answer - a = sulfur

The correct option is (a).

Explanation:

Non metallic minerals : These are the minerals which do not contains metal elements. for example : graphite, quartz etc.

Sulfur is a non metallic mineral because :

It is a brittle yellow color crystalline solid , as non metals are brittle that is they are easily breakable.it forms acidic oxides as non metals usually forms acidic oxides.It do not conduct electricity as non metal did not conduct electricity.

Whereas other are examples of metals.

Wish i can but don’t know this

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.