Question

An ion which imparts brick red colour to the flame and pale green colour to through blue glass is:
(A) calcium
(B) sodium
(C) potassium
(D) magnesium

Answer 1

Hint: The elements which impart the brick red colour and pale green colour through blue glass have an atomic mass of 40 a.m.u and its ion has 20 protons and 18 electrons in it. When the ion is exposed to the heat r=that is non-luminous heat then it produces colour similar to cadmium.

Complete step by step solution:
From your chemistry lessons, you have learned about the flame test and here we have to find which element will impart brick red colour in a flame test and pale green colour to blur glass.
A flame test is a test in which the element is exposed with the non-luminous flammable heat and then the electrons present in it exit to the higher state and emit the light.
The electron exits due to the absorption of energy given by the light and because of this the colour of the flame becomes coloured.
In the question, the element that gives the colour is calcium in the form of ion and the calcium ion is formed when two electrons are lost by calcium atom.
So, when calcium ion undergoes flame test the electrons of the calcium emits brick red colour and dye top this flame also becomes brick red.
And when calcium is pass through the blue glass is emits pale green colour
Where the sodium emits intense yellow colour
Potassium atom emits lilac colour instead of brick red and magnesium emits no colour.

Thus the correct option is (A).

Note: Magnesium emits no colour during the flame test but if you will burn magnesium metal it will emit intense white colour. In the flame test information about the quality of the electrons is given but not about the quantitative data. To neglect the yellow flame of sodium when impurities are present in the molecule then we use the cobalt blue glass to see the flame.