The melting and boiling points of alkali metal halides always follow the trend ,

Options

A. Iodide gt bromide gt chloride gt fluoride
B. Bromide gt chloride gt iodide gt fluoride
C. Fluoride gt chloride gt bromide gt iodide
D. Chloride gt fluoride gt bromide gt iodide

Answer

C

Explanation

For the same alkali metal ion, the lattice enthalpies decrease as the size of the halide ion increases. As the lattice enthalpies decrease, energy required to break the lattice (melting point) decreases and, hence, the melting points of alkali metal halides decrease from fluoride to iodide.