A shiny brown coloured element ‘X’ on heating in the air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.

Answer: copper

The shiny brown coloured element is Copper metal. As copper is heated in the air, it reacts with oxygen in the air to form black coloured copper oxide.

2Cu(s) + O₂(g) → 2CuO(s)

Copper(Cu)

Copper(Cu) is a chemical element with atomic number 29. It can be classified as a native metal that can occur in nature in its pure form. Few properties of copper are tabulated below.

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Refer more

• Identify the substances that are oxidized and that are reduced in the following equation. (i) 4Na(s) + O₂(g) → 2Na₂O(s) (ii) CuO(s) + H₂(g) → Cu(s) + H₂O(l)
• What is the chemical formula for corrosion in copper and silver?