Question

Which is the most stable halide of alkali metal?

• A. Sodium fluoride
• B. Sodium bromide
• C. Sodium chloride
• D. Sodium iodide

Answer 1

The correct option is A Sodium fluoride

Element	$MF$	$MCl$	$MBr$	$MI$
$Li$	-612	-398	-350	-271
$Na$	-569	-400	-360	-288
$K$	-563	-428	-392	-328
$Rb$	-549	-423	-389	-329
$Cs$	-531	-424	-395	-337

Standard enthalpies of formation in (kJ/mol) are given below.
The value decreases in the order: Fluoride > Chloride > Bromides > Iodide.
Thus, fluorides are the most stable while iodides are the least stable.