Answer: C) Organisms and their Environment Explanation: Ecology is the branch of science which deals with the study of Ecosystem (relation between the Organisms and their Environment.)

Answer: D) Defence Research and Development Organisation Explanation: DRDO stands for The Defence Research and Development Organisation.   The Defence Research and Development Organisation (DRDO) is an agency of the Republic of India, charged with the military's research and development, headquartered in New Delhi, India.

Answer: C) Mobilephone Explanation: Given 8, 9, 1, 11 letters indicates HOME which is residence 7, 2, 9, 5 indicates POOL where we can swim 1, 4, 5, 11 indicates MILE which is unit of distance 10, 9, 3, 6, 5 is NOBEL which is an International Prize 6, 11 are 'e' and 2, 9 are 'o' are same With all the above hints the word is MOBILEPHONE.

Answer: A) Land revenue reforms Explanation: Todar Mal was associated with land revenue reforms.   Raja Todar Mal was the Finance Minister of the Mughal empire during Akbar's reign. He was one of the Navaratnas in Akbar's durbar.

In Heights and Distances, The angle of elevation of an object is the angle between the horizontal and the line of sight that is the line from the object to the observer's eye.

Answer: C) Gamma Explanation: Cobalt therapy or cobalt-60 therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer.   Cobalt 60 is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. It is produced artificially in nuclear reactors.

Answer: D) P.S. Krishnan Explanation:

Answer: A) Rs. 4000 Explanation: Let C's salary be Rs. x Then B's salary = 80x/100 => A's salary = (50/100) * (80x/100) = 40x/100 But given total earnings in a month = 22000 => x + 80x/100 + 40x/100 = 22000 => x + 120x/100 = 22000 => x = 10000 => A's salary = 40 x 10000/100 = Rs. 4000