Some Basic Conc...

What is the mass per cent of oxygen in ethanol?

0.2 g of an organic compound contains $$C,\ H,\ O$$ on combustion, it yields 0.15 g of $$CO_2$$ and 0.12 g $$H_2O$$. The percentage of $$C,\ H$$ and $$O$$ respectively is:

Calculate the mass percent (w/w) of sulphuric acid in a solution prepared by dissolving $$4$$ g of sulphur trioxide in a $$100$$ml sulphuric acid solution containing $$80$$ mass percent (w/w) of $$H_2SO_4$$ and having a density of $$1.96\ g/ml$$(molecular weight of $$H_2SO_4=98$$) Take reaction $$SO_3+H_2O\rightarrow H_2SO_4$$.

Mole fraction of ethyl alcohol in aqueous ethyl alcohol $$(C_2H_5OH)$$ solution is $$0.25$$. Hence percentage of ethyl alcohol by weight is:

32 g of a sample of $$FeSO_4$$.$$7H_2O$$ were dissolved in dilute sulphuric acid and water and its volume was made up to 1 litre. 25 mL of this solution required 20 mL of 0.02 M $$KMnO_4$$ solution for complete oxidation. Calculate the mass % of $$FeSO_4$$.$$7H_2O$$ in the sample.

Carbon occurs in nature as a mixture of $$^{12}C$$ and $$^{13}C$$. The average atomic mass of carbon is 12.011. What is the % abundance of $$^{12}C$$ in nature?

An organic compound contains 69% carbon and 4.8% hydrogen, the remainder being oxygen. What will be the masses of the carbon dioxide and water produces when 0.20g of this substance is subjected to the complete combustion?

A mixture of $$NaHCO_3$$  and $$Na_2CO_3$$ weighs 950 gm. When the mixture is heated strongly in an open vessel, till constant weight, the mass of sample reduced by 155 gm. The correct information(s) is/ are ?

P and Q are two elements which form $${ P }_{ 2 }{ Q }_{ 3 }$$ and $${ PQ }_{ 2 }$$. If 0.15 mole of $${ P }_{ 2 }{ Q }_{ 3 }$$ weight 15.9 g and 0.15mole of $${ PQ }_{ 2 }$$ weight 9.3 g. what are atomic weights of P and Q respectively?