Is nuts and bolts an example of a pure substance or a mixture?

Nitrogen (n), phosphorus (p), and potassium (k) are the main nutrients in plant fertilizers. according to an industry convention, the numbers on the label refer to the mass percents of n, p2o5, and k2o, in that order. calculate the n: p: k ratio of a 30: 10: 10 fertilizer in terms of moles of each element, and express it as x: y: 1.0.

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?

The excretory system, need answers for all: )