Question

what is the molar mass for ca(oh)2? 72.092 g/mol 70.092 g/mol 79.092 g/mol 74.092 g/mol

Explanation:

Step1: Find atomic masses

Ca: $40.078$ g/mol, O: $15.999$ g/mol, H: $1.008$ g/mol.

Step2: Calculate for each atom

In $\ce{Ca(OH)2}$, 1 Ca, 2 O, 2 H.
Ca: $1\times40.078 = 40.078$
O: $2\times15.999 = 31.998$
H: $2\times1.008 = 2.016$

Step3: Sum the masses

Total = $40.078 + 31.998 + 2.016 = 74.092$ g/mol.

Answer:

74.092 g/mol (corresponding to the red option: 74.092 g/mol)