Identify the elements from the following characteristics and arrange them in increasing order of metallic character.
(a) An element which imparts golden yellow colour to the flame.
(b) An element whose oxide is used as a white wash.
(c) An element which is constituent of of chlorophyll i.e. green colouring matter in plants.

Explanation

(a) Sodium (b) Calcium (c) Magnesium. Element sodium (Na) belongs to group 1. Both calcium (Ca) and magnesium (Mg) are present in group 2. The element Ca is placed below Mg in the group. Since the metallic character of the elements decreases along a period and increases down the group, in the light of these observations, the increasing order of metallic character is : `MgltNaltCa.`