Which of the following statements are incorrect?
I. Reactivity of Al decreases if it is dipped in nitric acid.
II. Carbon can reduce the oxides of Na and Mg.
III. NaCl is a good conductor of electricity in solid state.
IV. Metals like K, Ca and Mg are always found in free state in nature.
A I, II and III only
B II, III and IV only
C I and III only
D II and III only
common salt can never conduct electricity in solid state