Chemistry Worksheet Class 11 on Chapter 1 Some Basic Concepts of Chemistry with Answers - Set 3

Chemistry is a branch of science that studies matter and the substances that makeup matter. It also discusses the properties of these substances as well as the reactions that occur when they combine to form new substances. Chemistry is primarily concerned with atoms, ions, and molecules, which combine to form elements and compounds. Chemical bonds allow these chemical species to interact with one another. It is worth noting that the interactions of matter and energy are also investigated in the field of chemistry.

Chemistry is the study of the properties, compositions, and structures of elements and compounds, as well as how they can change and the energy that is released or absorbed during such changes.

Download PDF of Class 11 Chemistry Chapter 1 Some Basic Concepts of Chemistry – Set 3

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CBSE Class 11 Chemistry Worksheet Chapter 1 Some Basic Concepts of Chemistry – Set 3

Q1. In a hydrocarbon, the mass ratio of hydrogen and carbon is 1:3; the empirical formula of hydrocarbon is ____.

a.) CH₄

b.) CH₂

c.) C₂H

d.) CH₃

Q2. 80g of oxygen contains as many atoms as in ____.

a.) 10 g of hydrogen

b.) 5 g of hydrogen

c.) 8 g of hydrogen

d.) 1 g of hydrogen

Q3. A mixture of gases contains H₂ and O₂ gases in the ratio 1:4. What is the molar ratio of the two gases in the mixture?

a.) 16:1

b.) 2:1

c.) 1:4

d.) 4:1

Q4. Which of the following concentration terms is/are independent of temperature?

a.) Molality

b.) Mole fraction

c.) Molarity

d.) Normality

Q5. Which of the following contains the highest number of atoms?

a.) 1.0 g of water

b.) 1.0 g of silver

c.) 1.0 g of nitrogen

d.) 1.0 g of propane

Q6. What physical quantities are represented by the following units, and what are their common names?

i.) kg m² s^–2

ii.) kg m s^–2

iii.) dm²

Q7. What do you understand by the following terms?

i.) Empirical formula

ii.) Molecular formula

Q8. State the law of multiple proportions.

Q9. Define elements, compounds and mixtures.

Q10. Express the following up to three significant places:

a.) the height of a man, 5 feet 9 inches in centimetres (1 inch = 2.54 cm)

b.) one-millionth of one

c.) four thousand

d.) decimal equivalent of ⅔

Q11. a.) Balance the following equations:

i.) 4H₃PO₃ → 3H₃PO₄ + PH₃

ii.) Ca + 2H₂O → Ca(OH)₂ + H₂

iii.) Fe₂(SO₄)₃ + 3NH₃ + 3H₂O → 2Fe(OH)₃+ 3(NH₄)₂SO₄

b.) Write the empirical formulae of the compounds having the following molecular formulae:

i.) C₆H₆

ii.) H₂O₂

iii.) Na₂CO₃

Q12. Two oxides of metal contain 27.6% and 30% of oxygen, respectively. If the formula of the first compound is M₃O₄, find the formula of the second compound.

Q13. Calculate the difference in the number of carbon atoms in 1.0 g of C –14 isotope and 1.0 g of C – 12 isotope.

Q14. Calculate the percentage yield of the reaction if 64 g NaBH₄ reacts with iodine to produce 15.0 g of BI₃.

Q15. Calculate the number of atoms of each type in 5.3 g of Na₂CO₃.

Q16. 3.0 g of H₂ reacts with 29.0 g of O₂ to yield H₂O.

i.) Which is the limiting reactant?

ii.) Calculate the amount of H₂O that can be formed,

iii.) Calculate the amount of one of the reactants which remains unreacted.

Q17. Commercially available sulphuric acid contains 93% acid by mass and has a density of 1.84 g mL^–1.

Calculate-

i.) Molarity of the solution

ii.) The volume of concentrated acid required to prepare 2.5 L of 0.50 M H₂SO₄.

Q18. A solid mixture (5.0 g) consisting of lead nitrate and sodium nitrate is heated below 600℃ until the weight of the residue is constant. If the loss in weight is 28%, calculate the amount of lead nitrate and sodium nitrate in the mixture.

Q19. Calculate the empirical formula and molecular formula of the compound having the following percentage composition:

Na = 36.5%, H = 0.8%, P = 24.6%, O = 38.1%

The molecular mass of the compound is 126 amu. Also, name the compound.

Q20. 2.5g of an impure sample of sodium bicarbonate, when heated strongly, gave 300 ml of carbon dioxide measured at 27℃ and 760 mm pressure. Calculate the percentage purity of the sample.

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