Vitamin d is an organic molecule that regulates the absorption of calcium by the body. which of the following elements is most common in a molecule of vitamin d?

a. aluminum
b. carbon
c. magnesium
d. sodium

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Drag each label to the correct location on the table. each label can be used more than once. decide whether each statement describes saturated fat, unsaturated fat, or both saturated and unsaturated fats.

Which statement is the best summary of the model? a-a series of aerobic and anaerobic reactions take place in cells b- the sun's energy moves through trophic levels in a food chain c-light energy is converted into stored chemical energy plants.d- food molecules are broken down in the cells if living things.