Answer: C) The number of protons is equal to the number of electrons. Explanation: The number of protons is equal to the number of electrons. That is the number of positive charges is equal to the number of negative charges.

Answer: D) 320 m Explanation: Relative speed = (72 - 36) x 5/18 = 2 x 5 = 10 mps.Distance covered in 32 sec = 32 x 10 = 320 m. The length of the faster train = 320 m.

Answer: A) Air pollution Explanation: 1. Lichens are plants that grow in exposed places such as rocks or tree bark.   2.  Lichens are widely used as environmental indicators or bio-indicators. They can be used as air pollution indicators, especially of the concentration of sulfur-di-oxide in the atmosphere.     3. They need to be very good at absorbing water and nutrients to grow there.

Answer: A) Saturday Explanation: 350 days, 350/7 = 50, no odd days, so it will be a Saturday.

Answer: B) 1 hr 20 min Explanation: Let the distance and original speed be 'd' km and 'k' kmph respectively. d/0.8k - d/k = 20/60 => 5d/4k - d/k = 1/3 => (5d - 4d)/4k = 1/3 => d = 4/3 k Time taken to cover the distance at original speed = d/k = 4/3 hours = 1 hour 20 minutes.

Answer: A) 27 sec Explanation: Time taken to meet for the first time anywhere on the track = length of the track / relative speed = 300 / (15 + 25)5/18 = 300x 18 / 40 x 5 = 27 seconds.

Answer: C) 52.66 kgs Explanation: Given total number of passengers in the bus = 45 First average weight of 45 passengers = 52 kgs Average weight of 5 passengers who leave bus = 48 Average weight of 5 passengers who joined the bus = 54 Therefore, the net average weight of the bus is given by = 45 x 52 - 5 x 48 + 5 x 5445 = 237045= 1583= 52.66 kgs.

Answer: D) 78 yrs Explanation: Let Hari Ram's present age = x Then, his son's age = x/3 Father's age = 5x/2 x + x3 + 52x3 = 46=> x = 36 yrs Now the required difference = 52x36 - 363 = 78 yrs