Case Study Questions for Class 12 Chemistry Chapter 7 The p-Block Elements

There is Case Study Questions in class 12 Chemistry in session 2020-21. For the first time, the board has introduced the case study questions in the board exam. The first two questions in the board exam question paper will be based on Case Study and Assertion & Reason. The first question will have 5 MCQs out of which students will have to attempt any 4 questions. The second question will carry 5 Assertion & Reason type questions with the choice to attempt any four. Here are the questions based on case study.

Case Study Question 1:

Read the passage given below and answer the following questions:

Ozone is an unstable, dark blue diamagnetic gas. It absorbs the UV radiation strongly, thus protecting the people on earth from the harmful UV-radiation from the sun. The use of chlorofluorocarbon (CFC) in aerosol and refrigerator and their subsequent escape into the atmosphere, is blamed for making holes in the ozone layer over the Antarctica. Ozone acts as a strong oxidising agent in acidic and alkaline medium. For this property, ozone is used as a germicide and disinfectant for sterilizing water. It is also used in laboratory for the ozonolysis of organic compounds and in industry for the manufacture of potassium permanganate, artificial silk, etc.

The following questions are multiple choice question. Choose the most appropriate answer:

(i) Which of the following statements is not correct for ozone?
(a) It ixidises lead sulphide
(b) It oxidises potassium iodide
(c) It oxidises mercury
(d) It cannot act as bleaching agent in dry state.


Ozone gives carbonyl compounds with
(a) alkyl chloride
(b) alkanes
(c) alkenes followed by decomposition with Zn/ H2O
(d) alcohols followed by decomposition with Zn/H2O.

(ii) Ozone reacts with moist iodine gives
(a) HI
(b) HIO3
(c) I2O5
(d) I2O4

(iii) Ozone acts as an oxidising agent due to
(a) liberation of nascent oxygen
(b) liberation of oxygen gas
(c) both (a) and (b)
(d) none of these

(iv) The colour of ozone molecule is
(a) white
(b) blue
(c) pale green
(d) pale yellow

Answer (i) d
or c
(ii) b
(iii) a
(iv) b

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