Question

Alkaline earth metal(s) which does (do) not
impart colour to the flame is (are):

• A. Be
• B. Mg
• C. Ca
• D. Sr

Answer 1

Answer: (A), (B)

The correct options are
A Be
B Mg

Beryllium($Be$) and magnesium($Mg$) cannot give flame test. They have small size. They strongly binds their electrons. Thus they have high ionization enthalpies. The thermal energy of flame is not sufficient to excites their electrons.