Class 11th

3.32. Predict the formulas of the stable binary compounds that would be formed by the combination of the following pairs of elements:

(a) Lithium and oxygen             

(b) Magnesium and nitrogen

(c) Aluminium and iodine         

(d) Silicon and oxygen

(e) Phosphorous and fluorine   

(f) Element 71 and fluorine.

Questions and Answers:

14.1. Which acid is most abundant in acid rain?

14.5. Photochemical smog occurs in

(a) Warm, dry and sunny climate (b) cool (c) humid (d) none of the above.

14.29 Read the following statements carefully. Select the incorrect statement.

(a) Besides carbon dioxide, other greenhouse gases are methane, water vapour, nitrous oxide, CFCs and ozone.

(b) Methane is produced naturally when vegetation is burnt, digested or rotted in the absence of oxygen.

(c) Large amounts of methane are released in paddy fields, coal mines, from rotting garbage dumps and by fossil fuels.

(d) Methane are man-made industrial chemicals used in air conditioning etc.

14.28 The pollutant responsible for Bhopal gas tragedy was
(a) Ammonia (b) Methyl isocyanate (c) Nitrous oxide (d) Mustard gas

14.2 The main constituents of air are

(a) N₂ and O₂ (b) SO₂ and CO₂ (c) CO and CO₂  (d) none of the above

MCQs

14.26  Which of the following statements is incorrect?

(a) The atmosphere that surrounds the earth isnot of the same thickness at all heights. 

(b) The lowest regionof atmosphere in which the human beingsalong with other organisms live is calledtroposphere.

(c) Below the troposphere,between 10 and 50 km above sea level lies stratosphere.

(d) Troposphere is a turbulent, dusty zone containing air, much water vapour and clouds.

14.3 Assertion: Tetra chlroroethene was earlier used as solvent for dry cleaning, which now a days are discontinued.

Reason: Chlorine gas was used earlier for bleaching.

14.22 Assertion: CO is a colourless and odourless gas, highly poisonous to living beings.

Reason: It is produced as a result of incomplete combustion of carbon and is mainly released into the air by automobile exhaust.

Assertion and Reason:

Directions:

(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.

(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.

(c) Assertion is correct statement but reason is wrong statement.

(d) Assertion is wrong statement but reason is correct statement.

14.21 Assertion: Atmosphere trapping the sun’s heat near the earth’s surface is called natural greenhouse effect. 

Reason: Atmosphere trapping the sun’s heat maintains the temperature and makes the earth perfect for life.