An alkali metal (M) forms ion of the general formula
M+
M-
M2-
M2+
Which of the following gives a green colour to flame?
Barium
Calcium
Strontium
Cerium
Which of the following reaction is not feasible?
2KI + Br2 → 2KBr + I2
2H2O + 2F2 → 2HF + O2
2KBr + I2 → 2KI + Br2
2KBr + Cl2 → 2KCl + Br2