What determines the property of hardness in a mineral?

Which of the following is true for the actual yield of a reaction? it is always calculated as a ratio. it is the yield from the excess reactant. it is the yield from the limiting reactant. it is always less than the theoretical yield.

Fill in the coefficients that will balance the following reaction: a0cr2(so4)3 + a1agno3 -> a2cr(no3)3 + a3ag2so4

Enzymes affect the reactions in living cells by changing the