Some Basic Conc...

$$1g$$ of a sample of brass om reacting with excess HCI produces $$120 ml$$ of $${ H }_{ 2 }$$ gas at STP. The percentage Zn in this sample of brass is: (At.wt.of Zn-=$$65.5g$$)

In $$500$$ grams of water dissolved 2 moles of potassium sulphate the mass precentage of salt in soluton:

Calculate the mass of iron which will be converted into its oxide $$(Fe_3O_4)$$ by the action of $$8g$$ of steam on it. [At mass of $$Fe = 56$$]
$$Fe + H_2O \rightarrow Fe_3O_4 + 4H_2$$

Vapour density of the equilibrium mixture of $${ NO }_{ 2 }$$ and $${ N }_{ 2 }{ O }_{ 4 }$$ is found to be 40 for the equilibrium: 

At $$0^{\circ}C$$ the density of gaseous oxide at 2 bar is same as that of nitrogen at 5 bar and $$0^{\circ}C$$. The molar mass of the oxide is (assuming ideal behaviour): 

Four one litre flasks are separately filled with gases $$O_2, F_2, CH_4$$ and $$CO_2$$ under same conditions. 

What is the mass of the precipitate formed when $$50$$ mL of $$16.9$$ % $$(w/v)$$ solution of $$AgN{ O }_{ 3 }$$ is mixed with $$50$$ mL of $$5.8$$% $$(w/v)$$ $$NaCl$$ solution? 

According to Avogadro's law the volume of a gas will ____ as _____ if ____ are held constant.

A 1.50 g sample of an ore containing silver was dissolved,and all the $$ Ag^{+} $$ was converted to 0.125 g $$ Ag_{2}S $$. What was the percentage of silver in the ore?