646: The most reactive among the halogens is

(a) fluorine

(b) chlorine

(c) bromine

(d) iodine
647: Which one of the following countries is land locked?

(a) Bolivia
(b) Peru
(c) Suriname
(d) Uruguay
648: The ideal climatic conditions for the cultivation of rice are

(a) rainfall above 100 cm, temperature above 25°C

(b) cool and moist climate for the entire crop period

(c) rainfall below 100 cm, temperature below 25°C

(d) warm and dry climate during the entire crop period
649: With reference to the use of nano-technology in health sector, which of the following statements is/are correct?

1. Targeted drug delivery is made possible by nanotechnology.
2. Nanotechnology can largely contribute to gene therapy.

Select the correct answer using the code given below.
(a) 1 only
(b) 2 Only
(c) Both 1 and 2
(d) Neither 1 nor 2
650: If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?

(a) 6
(b) 7
(c) 14
(d) 21