Sulphuric acid used in Lead Storage battery has a concentration of $$4.5 \mathrm{~M}$$ and a density of $$1.28 \mathrm{~g} / \mathrm{~ml}$$. The molality of the acid is __________.

A given mass of a hydrocarbon on complete combustion produced $$176 \mathrm{~g}$$ of $$\mathrm{CO}_2$$ and $$90 \mathrm{~g}$$ of $$\mathrm{H}_2 \mathrm{O}$$. What is the Molecular formula of the compound?

$$15 \mathrm{~g}$$ of $$\mathrm{CaCO}_3$$ completely reacts with

$$\mathrm{Mg}(\mathrm{OH})_2$$ is used as an antacid. If a person, suffering from acidity, produces $$2.5 \mathrm{~L}$$ of Gastric juice in a day, approximately how many antacid tablets, each containing $$600 \mathrm{~mg}$$ of $$\mathrm{Mg}(\mathrm{OH})_2$$, will be required to completely neutralise the whole $$\mathrm{HCl}$$ produced in the stomach in one day? (Gastric juice contains $$3.0 \mathrm{~g}$$ of $$\mathrm{HCl}$$ per L). (Atomic masses: $$\mathrm{Mg}=24 \mathrm{~g} / \mathrm{mol}, \mathrm{O}=16 \mathrm{~g} / \mathrm{mol}$$ & $$\mathrm{H}=1 \mathrm{~g} / \mathrm{mol}$$.)