Question

The equivalent mass of a certain bivalent metal is 20. The molecular mass of its anhydrous chloride is:

• A. 91 g/mole
• B. 111 g/mole
• C. 55.5 g/mole
• D. 75.5 g/mole

Answer 1

Answer: (B)

111 g/mole

The equivalent mass of a certain bivalent metal is 20. The molecular mass of bivalent metal will be double of the equivalent mass. It will be $2\times 20=40$.
The metal is bivalent. So 1 mole of metal atoms will combine with 2 moles of chlorine atoms.
$M+C{l}_2\to MC{l}_2$
The atomic mass of chlorine is 35.5 g/mol.
The molecular mass of its anhydrous chloride will be $40+2\left(35.5\right)=111$ g/mol.