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A 100% pure sample of a divalent metal c...

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

A

40

B

20

C

28

D

12

Text Solution

Verified by Experts

The correct Answer is:
B
Let the metal is M, so the formula of its carbonate is `MCO_(3)`.
Molar mass of `MCO_(3)=x+12+3xx16`
`=(x+60)g//mol`
(Let atomic mass of M is x.)
`{:(MCO_(3)overset(Delta)rarrMO+CO_(2)),("1 mol 1 mol = 22.4 L"),(" = 22400 mL"):}`
`because 448` cc (448 mL) `CO_(2)` is produced from carbonate = 2g.
`therefore 22400`cc `CO_(2)` will be obtained from carbonate
`=(2xx22400)/(448)=100g`
`therefore 100=x+60`
`x=100-60=40g//mol`
Eq. wt. of metal = `(40)/(2)=20g" equiv"^(-1)`
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