If $$20 \mathrm{~g}$$ of $$\mathrm{CaCO}_3$$ is treated with $$100 \mathrm{~mL}$$ of $$20 \%$$ $$\mathrm{HCl}$$ solution, the amount of $$\mathrm{CO}_2$$ produced is

A certain metal sulphide, MS₂, is used extensively as a high temperature lubricant. If MS₂ is 40.06% by mass sulphur, metal M has atomic mass.

In Victor Meyer's method 0.2 g of an organic substance displaced 56 mL of air at STP the molecular weight of the compound

The density (in g mL^$$-$$1] of a 3.60 M sulphuric acid solution that is 29% H₂SO₄ (molar mass = 98 g mol^$$-$$1) by mass will be