Important 3 Marks Questions for CBSE 11 Chemistry Exam

Ques 1:

Give reasons:

  1. LiCl is more covalent than KCl.
  2. In aqueous solution Li+ has lowest mobility.

Ques 2:

Describe in detail the expanded octet with suitable examples.

Ques 3:

(a)Give the importance of measuring BOD of a water body.

(b) What is desirable concentration of fluoride ion pH of drinking water?

(c) Calculate the pH of a buffer solution containing 0.2 mole of NH4Cl and 0.1 mole of NH4OH per litre. Given Kb for NH4OH = 1.85 X 10-5

Ques 4:

Explain the hybridisation of  SF4 ?

Ques 5:

(a) Calculate the total number of electrons present in one mole of methane.

(b) An atomic orbital has n = 3. What are the possible values of l and m?

Ques 6:

(a) The 4f subshell of an atom contains 12 electrons. What is the maximum [3] number of electrons having the same spin in it?

(b) Explain the meaning of 4p6.

(c) Write the electronic configuration of the atom with atomic number 20

Ques 7:

Kavita was playing a game with her friends. As a part of the game they asked her to express a wish. She said that she wanted to be able to see the atom. Atomic dimensions are from 10-12 m and nucleus is 10-15 m; visible range in the electromagnetic spectrum is for wavelengths in the range of 10-7m. As a student of chemistry

  1. Describe how the world would look for kavita if she is granted her wish.
  2. What value can you draw from this?

Ques 8:

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.40

Ques 9:

State Dalton’s law of partial pressure? A 5 lit vessel contains equal masses of methane and helium at 760 mmHg pressure, find the partial pressure each gas?

Ques 10:

The empirical formula of compound is CH2O and vapour density of that compound is 45. Then find the molecular formula of that compound?

Ques 11:

On complete combustion of 0.246 g of an organic compound gave 0.198 g of carbon dioxide and 0.1014g of water. Determine the percentage composition of carbon and hydrogen in the compound

Ques 12:

Explain the main features of VSEPR Theory

Ques 13:

What is Hund’s rule of maximum multiplicity? Explain by taking an example of nitrogen

Ques 14:

These people are not concerned with the health of other people.The first element in every group of representative elements shows properties different from the characteristic properties of the group.

  1. Name three such elements.
  2. Give two abnormal properties of each one of them.

Ques 15:

Professor of Delhi University found that some scraps emit high energy radiations which harmed large number of people. There are certain elements like Co-60 which emit radiations at their own and this phenomenon is called radioactivity. There are three kinds of rays.

  1. Name the ray which is used to treat cancer.
  2. Give the source of γ-rays used for treating cancer.
  3. Discuss the values not possessed by people disposing of radioactive waste materials

Ques 16:

Give reasons:

  1. Ethyne molecule is linear.
  2. Covalent bonds are directional while ionic bonds are non-directional.
  3. Water molecule has bent structure.

Ques 17:

How would you classify the state of chemical equilibrium in a chemical reaction based on the extent to which the reactions proceed?

Ques 18:

BARC at Trombay in Mumbai has five nuclear reactors which produce electricity. Boron rods are used as control rods to absorb neutrons in nuclear reactors, used for the production of electricity. Boron steel containers are used to dispose nuclear waste materials safely. Metal borides are used as protective shield.

  1. Give reason for the absorption of neutrons by boron.
  2. Give methods to dispose-of nuclear wastes safely.
  3. Give harmful effects of nuclear radiations
Test your Knowledge on Important 3 marks questions for cbse class 11 chemistry!

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