Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture? 

• The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic number down the group

• In both the alkali metals and the halogens the chemical reactivity decreases with increase in atomic number down the group

• Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens

• In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group

In a multi-electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic acid and electric fields?

(a) n = 1, l = 0, m = 0
(b) n = 2, l = 0, m = 0
(c) n = 2, l = 1, m = 1
(d) n = 3, l = 2, m = 1
(e) n = 3, l = 2, m = 0

• (a) and (b)

• (b) and (c)

• (c) and (d)

• (d) and (e)

In which of the following arrangements the order is NOT according to the property indicated against it?

• Al³⁺ < Mg²⁺ < Na⁺ < F^- Increasing ionic size

• B < C < N < O Increasing first ionization enthalpy

• I < Br < F < Cl Increasing electron gain enthalpy (with negative sign)

• Li < Na < K < Rb Increasing metallic radius

The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of the cationic species, K⁺, Ca²⁺, Mg²⁺, Be²⁺?

• Mg²⁺ < Be²⁺ < K⁺ < Ca²⁺

• Be²⁺ < K⁺ < Ca²⁺ < Mg²⁺

• K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺

• Ca²⁺ < Mg²⁺ < Be²⁺ < K⁺

The correct sequence which shows decreasing order of the ionic radii of the elements is

• Al³⁺ > Mg²⁺ > Na⁺ > F^- > O^2-

• Na⁺ > Mg²⁺ > Al³⁺ > O^2- > F^-

• Na⁺ > F^- > Mg²⁺ > O^2- > Al³⁺

• O^2- >F^- > Na⁺ > Mg²⁺ >Al³⁺