Carbon dioxide, oxygen, water, and acids may all cause chemical weathering. Mechanical weathering is the process of breaking a large rock into smaller pieces without changing the minerals in the rock. Mechanical weathering may be caused by frost, ice, plant roots, running water, or heat from the sun.
Answer:
Mass does not affect gravity and distance has an indirect relationship.
Explanation:
The equation for gravity is, g = 
where, G = gravitational constant
M = mass of the planet
R = distance between the bodies (object and center of planet)
so, gravity depends on the mass of planet, not on mass of object
and is inversely proportional to sqaure of distance.
Answer: Epidemiology
Explanation:
Epidemiology is a branch of medicine, the study of human health and disease at the population level. Epidemiology deals with the incidence, distribution, prevalence and possible control of diseases and other factors relating to health. By tracking the cause and distribution of the disease among many individuals of the population, epidemiologist can identify potential stategies for the preventing and controlling of diseases and disorders.