Class 7 Metals and Non-metals

_______ metal is non-malleable.

• Silver

• Gold

• Zinc

______ is the hardest natural substance.

• Graphite

• Diamond

• Charcoal

_______ is a liquid metal.

• Silver

• Gold

• Mercury

_________ is a non-metal which is a good conductor of electricity.

• Oxygen

• Iodine

• Graphite

________ is a soft metal.

• Sodium

• Copper

• Silver

When a metal reacts with oxygen in the presence of moisture and deteriorates, it is called _____________.

• decomposition

• corrosion

• physical change

Copper forms a green layer of ___________ on exposure to moist air.

• Copper hydroxide

• basic copper carbonate

• Copper phosphate

Rust is _________.

• hydrated ferrous oxide

• hydrated ferrous carbonate

• hydrated ferric oxide

The rate of rusting ___________ with an increase of acidic gases.

• decreases

• increases

• does not change

The process of applying a thin layer of Zinc metal on iron objects is called

• greasing

• rusting

• galavanisation