What are the five basic requirements to make a space station habitable?

The five basic requirements are:

Explanation:

Breathable air - This is essential because humans need breathable air in order to live.

Nutritious food and water -  This is essential because humans need to eat the right food in order to get the necessary nutrients to keep their bodies healthy. Water is essential as it hydrates the body.

A place to get rid of waste - This is essential because waste carries a lot of bacteria that can make humans sick, so it essential that it can be disposed of to prevent illnesses etc.

Personal hygiene - This is essential because humans need to keep clean and fresh so that bacteria does not cause illness. Things such as brushing your teeth is a must in order for your teeth and gums to stay healthy.

Ways to keep in shape - Regular exercise is good for body and mind and it is also essential so that your bones and muscles don't become weak. There is no gravity in space, so it is important that you do exercise in order to function properly when you are exposed to gravity.

conservation of mass

mass before something happens = mass afterwards