Consider the following elements:
K, I, Li, Sr, CI, Mg, Br, Ca, Na.
Separate these elements in three groups or triads having similar properties. State one property in each case on the basis of which groups are separated.
These elements can be separated into three groups as given below:
(a) K, Li, Na—have valency of (+1).
(b) Sr, Mg, Ca—have valency of (+2).
(c) I, CI, Br—have valency of (-1).