The formula to calculate population density is given by dividing the total population by the total land area.

Here are the answers to the questions:

1. The formula to calculate population density is given by dividing the total population by the total land area. $$\text{Population Density} = \frac{\text{Total Population}}{\text{Total Land Area}}$$
2. One cause of post-neonatal mortality rate is infectious diseases such as pneumonia or diarrhea.
3. Social taboos can negatively affect birth by discouraging women from seeking professional medical help during childbirth, leading to complications.
4. Two measures for managing gender equity in society are promoting equal access to education for all genders and ensuring equal opportunities in employment.
5. AIDS stands for Acquired Immunodeficiency Syndrome.
6. Two barrier methods of contraception are male condoms and diaphragms.
7. Geriatric care refers to specialized healthcare that focuses on the unique health needs and well-being of older adults.
8. The De-jure method of census counts individuals based on their usual place of residence, regardless of where they were physically present on the census day.
9. The first census in Nepal was taken in 1911 A.D.
10. The last goal (Goal 17) of the Sustainable Development Goals is Partnerships for the Goals.
11. The median is the middle value in a dataset when the values are arranged in ascending or descending order.