The kerosene oil sprayed on the water provodes a thin cating and the larvae of the mosquitoes are prevented from coming up to breathe. Thus, they die.
Hence, A is true but R is false.

The problem of pumping out water from the flooded mines provided the need of self-working engine, which led James Watt to invent the same.
Thus, both A and R are true & R correctly explains A.

Magnesium chloride present in common salt is a deliquescent substance i.e. it absorbs moisture from the air when kept in open. 

Rainfall in Tamil Nadu is caused by the retreating monsoons which occur in winter. 

litutmish was a ruler of slave dynasty and Razia was his daughter. 

The Indian Constitution came into force with effect from January 26, 1950 and since then this day is celebrated as the Republic Day.  

Silver is a good conductor of electricity but it is not used to make electric wires because it is expensive 

Vaccines prevent diseases by developing immunity inside the body and vaccines must be given to children to build in them a resistance against diseases. 

 Shivaji initiated the guerilla warfare to defeat the Mughuls but he did not fear them. 

Himalayas are the young fold mountains that at one time are believed to lie inside the Tethys sea. This is evident from the recovery of fossils of marine creatures on its peaks.