Question

A ribbon of silvery white element when heated in a flame , burns with a dazzling white light , and leaves a white powder. The white powder when dissolved in water turns red litmus blue.

Identity the the element and the white powder obtained on its burning.

Answer 1

Magnesium.(Mg)
And
The powder is Magnesium Oxide(MgO)

Answer 2

The given element is magnesium and the white powder obtained on burning it is magnesium oxide.

• A silvery white coloured element, available in the form of ribbon, is magnesium (Mg).

• On heating a magnesium ribbon, it burns in the oxygen present in air with a dazzling bright white light, which can cause damage to the naked eyes.

• After the entire ribbon is burnt, it leaves a white powder behind, which is magnesium oxide (MgO).

2Mg + O₂ →  2MgO

• On dissolving the powder of magnesium oxide in water, it forms magnesium hydroxide (Mg(OH)₂).

MgO + H₂O →  Mg(OH)₂

• Magnesium hydroxide is basic in nature, hence, turns moist red litmus paper blue.