True/False: Classification of Elements & Periodicity in Properties | JEE Advanced | 35 Years Chapter wise Previous Year Solved Papers for JEE PDF Download

Q.1. In group IA, of alkali metals, the ionisation potential decreases on moving down the group. Therefore, lithium is a strongest reducing agent. (1987 - 1 Mark) 

Ans. Sol. True : Ionisation energy decreases on moving down  in group IA from Li to Cs, the reducing property should increase in the same order, i.e., from Li to Cs which is found to be so except an anomaly in lithium which is found to be the strongest reducing agent; because of its higher oxidation potential (Eº).

Q.2. The decreasing order of electron affinity of F, Cl, Br is F > Cl > Br. (1993 - 1 Mark) 

Ans. Sol. False : Halogens have high electr on affinities which decrease as we move down the group. However, fluorine has lower value of E.A. than chlorine which is due to its small size and more repulsion between the electron added and electrons already present. Hence the order Cl > Br > F.

Q.3. The basic nature of the hydroxides of group 13 (Gr. III B) decreases progressively down the group. (1993 - 1 Mark)

Ans. Sol. False : On moving down the group 13 (III) A the basic nature of hydroxides increases. The basic nature increases as the element becomes more electropositive or acquires more metallic character when we move down a group.