What is the principal ore of calcium and magnesium​

Complete each row of the table below by filling in the missing prefix or missing exponent.

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.

How many oxygen atoms are there in 3.15 moles of hcl manganese (iv) oxide, mno2