Answer: D) Japan Explanation: Maglev trains are used in Japan, South Korea and China only. Maglev derived from magnetic levitation using the principle of magnetic repulsion is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track as in levitation then another set to move the 'floating train' ahead at great speed taking advantage of no friction. Maglev trains are therefore quieter and smoother than conventional trains, and have the potential for much higher speeds Despite over a century of research and development, maglev transport systems are in operation in just three countries Japan, South Korea and China.   Hence Maglev -- Magnetic-levitation.

Answer: A) Aditya Puri Explanation: American financial magazine Barron's has listed the name of HDFC Bank Managing Director Aditya Puri’s name in its list of world’s 30 best CEOs. He holds the 23rd position in the list beating social media giant Facebook’s CEO Mark Zuckerberg who is listed on the 30th spot.

Answer: A) gravitational pull Explanation: The atmospheric pressure at the surface of the Earth is due to gravitational pull of the earth and is about 14.7 psi.   That means that the weight of a column of air which has a cross section of 1 square inch and which stretches from the surface of the Earth to space is 14.7 pounds.

Answer: C) February Revolution Explanation: The fall of the Czar is known as February Revolution because, according to the old Russian calender, it occured on 27 February 1917.