Chemistry · Classification of Elements and Periodicity in Properties

Consider the following statements regarding the classification and properties of elements: (A) The chemical reactivity of an alkali metal increases down the group, whereas for halogens it decreases down the group. (B) Zinc, cadmium and mercury have the electronic configuration \( (n-1)d^{10}ns^2 \) and do not show typical transition metal properties. (C) The first ionization enthalpy of boron is slightly higher than that of beryllium due to stability of fully filled orbitals. (D) The ionic radius of a cation is always smaller than that of its parent atom due to loss of electrons and increased effective nuclear charge. Which of the above statements are correct?

1. (A) and (C) only
2. (A), (B) and (D) only
3. (B), (C) and (D) only
4. (A), (B), (C) and (D)