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. Answer the following:

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

Answer 1

1. The chemical reaction of burning a silvery-white element gives an oxide of that element.
2. The oxide of that element changed the red litmus blue.
3. Hence, it can be inferred that the oxide is that of a metal.
4. We know that Magnesium($\mathrm{Mg}$) is a silvery-white ribbon that burns and forms Magnesium oxide $\left(\mathrm{MgO}\right)$which is also a white-colored powder.
5. Hence, the reaction can be shown as follows:

$2\mathrm{Mg}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{MgO}\left(\mathrm{s}\right)$

Hence, the element is Magnesium and the white powder is Magnesium oxide.