Class 11th

14.37. BOD is a measure of

3.53. Why are electron gain enthalpies of Be and Mg positive?

Questions and Answers:

14.36. Which acid is most abundant in acid rain?

14.35. Photochemical smog occurs in

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

3.52. What is ionization enthalpy? Why is ionization enthalpy of nitrogen greater than that of oxygen?

14.34. 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

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

3.51. State the Modern Periodic Law.

14.32 The main constituents of air are 

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

MCQs

14.31 . 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.