From the list given below, select the correct substance which is most suitable to the given statements

(oxygen, diamond, zinc, graphite, gold)

(a) A metal which is brittle.

(b) A non-metal which is a good conductor of electricity.

(c) The hardest naturally occurring substance.

(d) The most ductile metal.

(e) A gaseous non-metal.

Classify the following substances into elements and compounds.

Mercury, sulphur, sugar, water, sand, gold, carbon, oxygen, alcohol, iron, marble, baking soda.

Give the names of the elements represented by the following symbols:

(a) B

(b) He

(c) Si

(d) Be

(e) Li

(f) P

(g) K

(h) F

Define a pure substance.