Define following terms :
(a) Birth rate
(b) Death rate.
(c)  Population density.
(d) Exhaustible resource
(e)  Rate of growth of population.

(a) Birth rate or natality is the number of live births per 1000 people of population per year
(b) Death rate or Mortality is the number of deaths per 1000 people per year.
(c) Population density is the number of individuals per square kilometre at any given time.
(d) Exhaustible resources are those resources which are present in limited quantity and can be completely used up by human activities are called exhaustible resources.
(e) Growth rate of the population is the difference between the birth rate and the death rate. As long as the birth rate exceeds the death rate, the population grows. If the birth rate is lower than the death rate, the population declines.