1 gram of a carbonate (M_{2}CO_{3}) on treatment with excess HCl produces 0.01186 mole of CO_{2}, The molar mass of M_{2}CO_{3} in g mol-1 is

(1) 118.6

(2) 11.86

(3) 1186

(4) 84.3

The equation for the above reaction is as follows:-

M2CO3 + 2HCl-> 2MCl+CO2+2H2O

This shows that ,

1 mole of CO2 is produced from -> 1 mole of M2CO3

Given that,

0.01186 mole of CO2 needs -> 1g of M2CO3

1 mole of CO2 needs -> (1g/0.01186mole)*1 mole = 84.31g

Hence, 84.31g being the mass of 1 mole of the carbonate is its molar mass.