Which of the following properties of elements of alkaline earth metal does not increase with increasing atomic number ?

Options

A. Stability of carbonate
B. Solubility of hydroxide
C. Reactivity with water
D. First ionization energy

Answer

D

Explanation

1. The thermal stability of oxyacid salts of alkali earth metals generally increases down the group decresing polarising power.
2. The solubility of the alkaline earth metal hydroxide increases down the group from Be to Ba. This is the fact that down the group with increasing size of the lattice energy as well as hydration energy also decreases but he change the latice energy is more as compare to that of hydration energy.
3. Down the group atomic size increases and therefore attraction between the valence shell electron and nucleus decrease: so ionisation enthalpy decreases . Hence they react with water with increasing vigour even the cold to from hydroxides from Be to Ba.
4. The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their first ionization enthalpy decreases.