Balance the following equations.
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A) Mg + H2SO4 → MgSO4 + H2

B) CaCO3 + 2HCl → CaCl2 + H2O + CO2

C) CaO + H2O → Ca(OH)2

D) 3Ag + 4HNO3 → 3AgNO3 + H2O + NO2

Explanation:

A) Mg + H2SO4 → MgSO4 + H2

The equation is already balanced because the number of each element in the left hand side is already equal to that in the right hand side.

B) CaCO3 + 2HCl → CaCl2 + H2O + CO2

This equation is balanced by putting 2 in front of HCl on the left hand side to balance the elements on the right hand side.

C) CaO + H2O → Ca(OH)2

Thus equation is already balanced because the number of each element in the left hand side is already equal to that in the right hand side.

D) 3Ag + 4HNO3 → 3AgNO3 + H2O + NO2

This equation is balanced by putting 3 in front of Ag and 4 in front of HNO3 on the left hand side while we put 3 in front of AgNO3 on the right side to balance the elements on the right hand side.