Mole concept - Home - :: Vishwa Bharti Public School

Difficulty Level: Average
Objectives & Skills: 1. Students are able to recall the concepts studied.
2. Students are able to apply the laws & solve the numericals
related to it.
Q1. What weight of sodium chloride is decomposed by 4.9g of sulphuric acid, if 6g of
sodium hydrogen sulphate (NaHSO4) and 1.825g of hydrogen chloride are produced
in the same reaction?
Q2. Copper gives two oxides. On heating 1g of each in hydrogen, we get 0.888g and
0.798g of the metal respectively. Show that these results are in agreement with the
Law of Multiple Proportions.
Q3. Copper Sulphate crystals contain 25.45% Cu and 36.075 H2O. If the law of
constant composition is true, calculate the weight of copper required to obtain
40g of crystalline copper sulphate.
Q4. The average atomic mass of Copper is 63.5. It exists as two isotopes which are
Cu and 65Cu.Calculate the percentage of each isotope present in it.
Q5 a) How many gram molecules are present in 4.9g of H2SO4?
b) Calculate the mass of 0.72 gram molecules of CO2.
Q6. Which has the maximum and minimum mass?
a) 25.6 of oxygen.
b) 2.56 gram atom of sodium. (at. mass = 23)
c) 0.256 gram molecule of water.
d) 0.256 gram atom of iodine. (at. mass = 127)
Q7. What is the number of molecules of CO2 which contains 8g of O2?
Q8.Calculate the volume at NTP occupied by
a) 14g of nitrogen
b) 1.5 gram moles of CO2
c) 1021 molecules of oxygen
Q9. An alloy of iron (53.6%), nickel (45.8%) and manganese (0.6%) has a density of
8.17 g cm-3. Calculate the number of Ni atoms present in the alloy of dimensions
10.0cm X 20.0cm X 15.0 cm.
Q10. An organic compound has the following percentage composition; C= 48%, H= 8%
O= 16% and N=28%. Calculate the empirical formula of the compound?
Q11. A crystalline compound when heated became anhydrous by losing 51.2% of the
mass. On analysis, the anhydrous compound gave the following percentage
composition: Mg = 20%, S = 26.66% and O = 53.33%.
Calculate the molecular formula of the anhydrous compound and crystalline
compound. The molecular mass of anhydrous compound is 120u.
Q12. The molecular mass of benzene is 78 amu. Its percentage composition is 92.31% C
and 7.69% H. Determine the molecular formula of benzene.
Q13. The reaction 2C + O2 ------------ 2CO is carried out by taking 24g of carbon and
96 g of O2. Find out:
a) Which reactant is left in excess?
b) How much of it is left?
c) How many grams of the other reactants should be taken so that nothing is left at
the end of the reaction?
Q14. a) A solution is prepared by dissolving 4g of NaOH to give 500ml of it. Calculate
the molarity of the solution.
b) What is the molality of a solution which contains 36g of glucose in 250g of H2O.
Q15. Calculate the molarity and normality of a solution containing 3.15g of hydrated
Oxalic acid (COOH .2H2O) dissolved in 250mL of the solution.
Q16. a) A solution is prepared by dissolving 3.65g of HCl in 500mL of the solution.
Calculate the normality of the solution.
b) Calculate the volume of this solution required to prepare 250 mL of 0.05N
Q17.a) A certain amount of a gas at 27oC and 1 bar pressure occupies a volume of 25m3.
If the pressure is kept constant and the temperature is raised to 77oC, what will be
the volume of the gas?
b) A human adult breathes in approximately 0.50dm-3of air at 1 bar with each
breath. If an air tank holds 100dm3 of air at 200bar, how many breaths the tank
will supply?Assume that the temperature is 37oC
Q18. A vessel of volume 8X 10-3 m3 contains an ideal gas at 300Kand 210kPa. The gas
is allowed to leak till the pressure falls to 135kPa. Calculate the amount of the gas
(in moles) leaked assuming the temperature to remain constant.
Q19. Calculate the mass of 0.120 dm-3 of N2 at 150oC and 0.987 bar pressure.
Q20. The mass of 0.5dm-3 of hydrogen at a pressure of 1 bar of Hg and at a temperature
of 300K was found to be 4X10-2g. Calculate the molar mass of hydrogen.