(i) The population growth rate is declining in India since 1981 because:

• The birth rate has declined rapidly.
• There is improvement in the education and literacy of females because they are aware of the fact of a small family.
• Better medical facilities have improved life expectancy at birth which helps in lowering the birth rate.
• Easy availability of birth controls and contraceptives.

(ii) There is three main components of population growth:

Birth rate: The birth rate refers to the number of live births per thousand persons in a year. It is a major component of growth because birth rates have always been higher than death rates in India. This indicates growth in both population size and density.

Death rate: Death rate refers to the number of deaths per thousand persons in a year. One of the main causes of overpopulation in India is the rapid decline in death rates.

Migration: Migration refers to the movement of people across regions and territories. Migration can be of two types: internal (within the country) or international (between the countries). Internal migration does not change the size of the population but changes the distribution of the population within the country. Whereas, international migration changes the size of the population of the country.

(iii) Age structure: The age composition of a population means the number of people in different age groups in a country. Age composition is one of the basic features of a population. To an extent, an individual's age affects what that person needs, buys, and does and also the capacity to perform various tasks.

Birth rate: The birth rate refers to the number of live births per thousand persons in a year.

Death rate: Death rate refers to the number of deaths per thousand persons in a year.

(iv) Migration refers to the movement of people across regions and territories. Migration can be of two types: internal (within the country) or international (between the countries. Migration plays a pivotal role in changing the size and distribution of the population. In India, most migrations have been from rural to urban areas because of the "push" factor in rural areas. This type of migration happens due to the adverse conditions prevailing in the rural areas such as poverty, unemployment, illiteracy etc. and the "pull" of the city in terms of increased employment opportunities and better living conditions. Migration is an important determinant of population change. It modifies not only the population size but also the population composition of urban and rural populations in terms of age and sex composition.