Chemistry by Ajay sir 9911995886

SOME BASIC CONCEPTS OF CHEMISTRY

Class 11 - Chemistry
Time Allowed: 1 hour Maximum Marks: 30

1. The molarity of NaOH in a solution prepared by dissolving its 4.0 g in enough water to form 250 mL of the [1]
solution is,

a) 0.002 M b) 0.4 M✔️

c) 0.04M d) 0.02 M

2. If 1 mL of water contains 20 drops then number of molecules in a drop of water is [1]

a) × 23 b) × 21
6.023 10 molecules 1.62 10 molecules✔️

c) × 20 d) × 26
4.346 10 molecules 1.376 10 molecules
3. Amount of sodium hydroxide present in 500ml of 0.2M solutions is : [1]

a) 4gm✔️ b) 40gm

c) 8gm d) 80gm

4. The mass of an atom of nitrogen in amu is, [1]

28
a) 6.023 ×1023 b)
1 23 g
14
6.023×10

c) 23 d) 14 amu ✔️
6.023×10

5. The number of moles of solute present in 1 kg of a solvent is called________. [1]

a) Mole fraction b) Molarity (M)

c) Molality (m) ✔️ d) ppm

6. What will be the molarity of pure water? [1]

a) 100 M b) 18 M ✔️

c) 55.6 M d) 50.0 M

-1 [1]
7. The density of 3 M solution of NaCl is 1.25gmL . The molality of the solution is:

a) 3.20 m b) 3.79 m

c) 2.79 m d) 3.00 m ✔️

8. The molar mass of C6H10O5 is: [1]

a) 172.09 u b) 182 g

c) 152.00 g/mol d) 162.14 g/mol ✔️

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9. 1 amu is equal to ________. [1]

a) of the mass of C-12 atom✔️ b) of the mass of N-14 atom

c) 1 g of H2 d) -23
1.66 × 10 kg
10. The empirical formula and molecular mass of a compound are CH2O and 180 g respectively. What will be the

[1] molecular formula of the compound?

a) C6H12O6✔️ b) C2H4O2

c) CH2O d) C9H18O9

11. The molar mass of CaCO3 is: [1]

a) 120 u✔️ b) 70g

c) 100 g /mol d) 90 amu

12. What is the mass of 1 molecule of O2? [1]

-23 b) -23
a) 4.32 × 10 g 6.32 × 10 g

c) -23 d) -23
7.32 × 10 g 5.32 × 10 g ✔️

× 23
13. One mole of any substance contains 6.022 10 atoms/molecules. Number of molecules of H2SO4 present in

[1]
the 100 mL of 0.02M H2SO4 solution is ________.

× 23 b) × 20
a) 6.022 10 molecules 12.044 10 molecules✔️

c) × 23 d) × 23
12.044 10 molecules 1 10 molecules
14. Molecular mass is the [1]

a) maximum of atomic masses of the elements

b) b) minimum of atomic masses of the elements present in a molecule.

c) average of atomic masses of the elements present in a molecule

d) sum of atomic masses of the elements present in a molecule. ✔️

15. 0.2 M NaOH solution means: [1]

a) 0.2 moles of NaOH in 100 mL of solution b) 0.2 moles of NaOH in 1 litre of solution ✔️

c) 0.2 moles of NaOH in 0.5 litre of solution d) 0.2 moles of NaOH in 10 mL of solution

16. An organic compound containing C and H has 92.3% of carbon, its empirical formula is [1]

a) CH3 b) CH ✔️

c) CH4 d) CH2

17. A solution is prepared by adding 2 g of a substance A to 18 g of water. Calculate the mass percent of the solute?
[1]

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 a) 10.00 % ✔️ b) 11.11 %

c) 0.50 % d) 1.01%

18. The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following
[1] element contains the greatest number of atoms?

a) 12g He ✔ b) 0.40g Ca

c) 46g Na d) 4g He

19. If 500 mL of a 5M solution is diluted to 1500 mL, what will be the molarity of the solution obtained? [1]

a) 0.017 M b) 1.59 M

c) 1.66 M ✔️ d) 1.5 M

–1 [1]
20. If the concentration of glucose (C6H12O6) in blood is 0.9 g L , what will be the molarity of glucose in blood?

a) 50 M b) 0.005 M ✔️

c) 0.5 M d) 5 M

21. How many atoms of hydrogen are in 67.2 L of H2 at STP? [1]

24 b) 24
a) 5.612 × 10 2.612 × 10

c) 24 d) 24
1.8066 × 10 ✔️ 4.612 × 10

22. The number of grams of oxygen in 0.10 mol of Na2CO3. 10H2O is [1]

a) 20.8 g b) 18 g

c) 10 g d) 12.8 g

23. In a homogeneous mixture, the components are: [1]

a) do not mix with each other and its b) do not mix with each other and its composition is uniform
throughout. composition is not uniform throughout.

c) completely mixed with each other and its d) completely mix with each other and its composition is
uniform throughout. composition is not uniform throughout.

24. The empirical formula of an acid is CH2O2, the probable molecular formula of acid may be [1]

a) C2H4O2 b) C3H6O4

b) c) CH2O2✔ d) CH2O

25. We have to prepare a Litre solution of 0.2 M NaOH from the available 1M solution. What volume of 1M NaOH
[1]
is required to be taken?

a) 2 mL b) 200 mL✔️

c) 0.2 mL d) 20 mL

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26. Molarity is defined as _________. [1]

a) the number of moles of the solute in 1 litre b) the number of moles of the solvent in 1 litre of the
solution of the solution✔️

c) the number of moles of the solute in 1 m3 of d) the number of grams of the solute in 1
litre the solution of the solution

27. The empirical formula of a compound is CH2. One mole of this compound has a mass of 42 g. Its molecular [1]

formula is

a) C2H2 b) C3H8

c) C3H6✔️ d) CH2

28. Molecular formula represents: [1]

a) ratio of masses of various atoms present in a compound

b) b) whole number ratio of different types of atoms present in a molecule of a compound
c) average fractionall ratio of various atoms present in a molecule of a compound

d) the exact number of different types of atoms present in a compound. ✔️

29. 5.6 litres of oxygen at STP is equivalent to: [1]

a) mole b) 1 mole

c) mole d) mole ✔️

30. The gram molar mass of H2SO4 is [1]

a) 68 g/mol b) 98 g/mol ✔️

c) 78 g/mol d) 49 g/mol

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