Q.Define density of population.

The estimated population of India between 2011 and 2025 is about 139.98 crores — option (c).

India's population, recorded at about 121 crores in the 2011 Census, has continued to grow. Official/projected estimates for the period 2011 to 2025 put the figure at approximately 139.98 crores (nearly 140 crores). Figures like 155 or 180 crores are far too high for this period, and 130 crores understates the projected value.

The state with the highest female population per 1000 males is Kerala — option (a).

The sex ratio measures the number of females per 1000 males. In most Indian states this ratio is below 1000, but Kerala is a notable exception with a favourable sex ratio (over 1000 females per 1000 males). This is linked to Kerala's high female literacy, better healthcare and greater social awareness. Maharashtra, Gujarat and Uttar Pradesh all have ratios lower than Kerala's.

Migration due to pull factors has a positive effect — option (b).

Migration is caused by two sets of factors:

• Push factors — unfavourable conditions (poverty, unemployment, drought) that force people to leave their place of origin; these usually have negative associations.
• Pull factors — favourable conditions (better jobs, higher income, education, facilities) that attract people to a new place.

Because pull factors reflect the attraction of better opportunities, migration driven by them is regarded as having a positive effect.

Australia is regarded as an under-populated nation.

A country's population may be at, above or below its optimum level. Under-population is when the population is much smaller than the level its resources could support, so resources remain under-utilised. Australia is the textbook example: it has a very large land area and rich natural resources but a comparatively small population and very low population density, so it is described as an under-populated country.

India's census is held every 10 years — option (a).

The Census of India is a decennial (once-in-ten-years) operation that counts the entire population and collects data on age, sex, literacy, occupation, migration and other characteristics. The first synchronous census was in 1881, and censuses have been conducted every ten years since, providing the base data for population and planning studies.

Gujarat's 2011 sex ratio was about 918 females per 1000 males — option (b).

The sex ratio is the number of females per 1000 males. As per the 2011 Census, Gujarat's sex ratio was around 918 females per 1000 males — well below the all-India figure (940), reflecting a relatively adverse ratio in the state. This is why improving the child sex ratio and women's status is a policy concern in Gujarat.

Death rate = number of deaths per 1000 persons of the population in a year.

The death rate (mortality rate) measures how many people die relative to the size of the population. It is calculated as:

$\text{Death rate} = \frac{\text{Number of deaths in a year}}{\text{Total (mid-year) population}} \times 1000$

It is expressed per thousand of population per year. A falling death rate, along with the birth rate, drives changes in the rate of population growth and is a stage in the demographic transition.

The correct option is (A) 7.1, India's death rate in 2011.

The crude death rate is the number of deaths per 1000 population in a year. Because of improvements in medical facilities, sanitation, nutrition and control of epidemics, India's death rate fell steeply over the decades and stood at about 7.1 per thousand in 2011. This large gap between a falling death rate and a comparatively higher birth rate is what kept the population growing rapidly.

India's last population census was held in 2011.

India carries out a population census once every ten years (decennial census). The last completed census was in 2011, which recorded a population of about 121 crore and provided key data on population growth, density, sex ratio and literacy used throughout the syllabus.

Development-based migration is population movement caused by large development projects (dams, industries, infrastructure) that either displace people or attract them to new opportunities.

Development-based migration refers to the migration of people that arises directly from development activities and projects. When large projects such as dams, reservoirs, industrial estates, highways, mines or new townships are built, people living in those areas may be displaced and have to move elsewhere; at the same time, such development also attracts workers and job-seekers toward the new centres of activity. Thus development itself becomes a cause of population movement.