Metals and Non-metals

Brittleness, Poor conductivity of electricity, Dull appearance

Non-metals are typically brittle (break into pieces when force is applied), poor conductors of electricity (except graphite), and have a dull appearance. Malleability and ductility are properties of metals.

True

Mercury is the only metal that exists as a liquid at room temperature. All other metals are solids at room temperature, though gallium and caesium have very low melting points.

Sodium > Iron > Zinc > Copper

According to the reactivity series, sodium is highly reactive (stored in kerosene), followed by iron, then zinc, and copper is least reactive among these. The reactivity series helps predict which metals can displace others from their salt solutions.

To prevent it from reacting with oxygen and moisture

Sodium is highly reactive and reacts vigorously with oxygen and moisture in air. It can even catch fire. To prevent accidental fires and oxidation, sodium is stored under kerosene oil, which prevents contact with air and moisture.