Q12 of 30 Page 1

Incomplete combustion of coal and petroleum:

(A) increases air pollution.


(B) increases efficiency of machines.


(C) reduces global warming


(D) produce poisonous gases


The correct option is :


it increases air pollution and produces poisonous gas.

For question numbers 13 and 14, two statements are given – one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a) (b), (c) and (d) as given below:

More from this chapter

All 30 →
10

At the time of short circuit, the electric current in the circuit:

(a) vary continuously (b) does not change


(c) reduces substantially (d) increase heavily


OR


Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be:


(a) 0.4 A (b) 0.6 A


(c) 0.8 A (d) 1 A


 11

Which one of the following is responsible for the sustenance of underground water?

 13

Assertion (A) : Esterification is a process in which a sweet smelling substance is produced.

Reason (R) : When esters react with sodium hydroxide an alcohol and sodium salt of carboxylic acid are obtained.


 14

Assertion (A) : In the process of nuclear fission, the amount of nuclear energy generated by the fission of an atom of uranium is so tremendous that it produces 10 million times the energy produced by the combustion of an atom of carbon from coal.

Reason (R) : The nucleus of a heavy atom such as uranium, when bombarded with low energy neutrons splits apart into lighter nuclei. The mass difference between the original nucleus and the product nuclei gets converted to tremendous energy.