1) they have similar chemical properties.
for example fluorine from the 17th column is a non metal so does all the elements of that group.
2)they have same valence electrons in their outermost shell
example
electronic configuration of
hydrogen 1, lithium 2,1, sodium 2,8,1 and so on.
3) have same valency.
BMI<span> (body mass index), which is based on the height and weight of a person, is an </span>inaccurate<span> measure of body fat content and does </span>not take into account muscle mass, bone density, overall body composition, and racial and sex differences. <span>BMI is a substitute measure of body fatness because it is a measure of excess </span>weight<span> rather than excess body </span>fat<span>. Factors such as age, sex, ethnicity, and muscle mass can influence the relationship between BMI and body </span>fat<span>.</span>
