Mole concept, molar mass and Avogadro's number — practice questions

Question 1 · difficulty L2 · understanding

0.25 g of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of $\mathrm{CaCl}_2$ tube and potash tube at the end of the experiment. The amount was found to be 0.15 g and 0.1837 g , respectively. The percentage of oxygen in compound A is $\_\_\_\_$ %. (Nearest integer) (Given: molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{H}: 1, \mathrm{C}: 12, \mathrm{O}: 16$ )

Question 2 · difficulty L2 · understanding

An organic compound weighing 500 mg , produced 220 mg of $\mathrm{CO}_2$, on complete combustion. The percentage composition of carbon in the compound is _________ $\%$. (nearest integer) (Given molar mass in $\mathrm{g} \mathrm{mol}^{-1}$ of $\mathrm{C}: 12, \mathrm{O}: 16$ )

Question 3 · difficulty L2 · understanding

Thyroxine, the hormone has given below structure The percentage of iodine in thyroxine is __________ %. (nearest integer) (Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{C}: 12, \mathrm{H}: 1, \mathrm{O}: 16, \mathrm{~N}: 14, \mathrm{I}: 127$ )

Question 4 · difficulty L2 · understanding

The amount of calcium oxide produced on heating 150 kg limestone ( $75 \%$ pure) is _________ kg. (Nearest integer) Given: Molar mass (in $\mathrm{g} \mathrm{mol}^{-1}$ ) of Ca-40, O-16, C-12

Question 5 · difficulty L2 · understanding

X g of nitrobenzene on nitration gave 4.2 g of m -dinitrobenzene. X = __________g. (nearest integer) [Given : molar mass (in $\left.\left.\mathrm{g} \mathrm{mol}^{-1}\right) \mathrm{C}: 12, \mathrm{H}: 1, \mathrm{O}: 16, \mathrm{~N}: 14\right]$

Question 6 · difficulty L2 · understanding

0.5 g of an organic compound on combustion gave 1.46 g of $\mathrm{CO}_2$ and 0.9 g of $\mathrm{H}_2 \mathrm{O}$. The percentage of carbon in the compound is _______________. (Nearest integer) [Given : Molar mass (in $\left.\mathrm{g} \mathrm{mol}^{-1}\right) \mathrm{C}: 12, \mathrm{H}: 1, \mathrm{O}: 16$ ]

Question 7 · difficulty L2 · understanding

Xg of benzoic acid on reaction with aq $\mathrm{NaHCO}_3$ released $\mathrm{CO}_2$ that occupied 11.2 L volume at STP. X is _________ g.

Question 8 · difficulty L2 · understanding

From $$6.55 \mathrm{~g}$$ of aniline, the maximum amount of acetanilide that can be prepared will be ________ $$\times 10^{-1} \mathrm{~g}$$.

Question 9 · difficulty L2 · understanding

$$\mathrm{Xg}$$ of ethylamine is subjected to reaction with $$\mathrm{NaNO}_2 / \mathrm{HCl}$$ followed by water; evolved dinitrogen gas which occupied $$2.24 \mathrm{~L}$$ volume at STP. X is _________ $$\times 10^{-1} \mathrm{~g}$$.

Question 10 · difficulty L2 · understanding

$$0.05 \mathrm{~cm}$$ thick coating of silver is deposited on a plate of $$0.05 \mathrm{~m}^2$$ area. The number of silver atoms deposited on plate are ________ $$\times 10^{23}$$. (At mass $$\mathrm{Ag}=108, \mathrm{~d}=7.9 \mathrm{~g} \mathrm{~cm}^{-3}$$)