A 100% pure sample of a divalent metal carbonate weighing 2 g on complete thermal decomposition releases 448 cc of carbon dioxide at STP. The equivalent mass of the metal is

Options

A. 40
B. 20
C. 28
D. 12

Answer

B

Explanation

Divalent metal carbonate means `MCO_(3)`

448 cc evolves from 2g
22400 cc will evolve from `(2)/(448 ) xx 22400 g = 100 g` i.e..,
100g is the molecular weight of the carbonate.
Then M.W. of metal ` = 100 (12 xx 3 xx 16)`
(wt. of carbonate `CO_(3)^(2-)`) = 40 g
Equivalent weight `= ("Molecular weight")/("Valency")`
` =(40)/(2) = 20`