Answer: C) Glass Explanation: Sound is a mechanical vibration and needs a medium for propagation. The higher the density of the medium, the faster the sound travels. So, sound cannot travel through vacuum.   As the sound travels faster in solids than liquids and gases, sound travels faster in the glass than Air and water.

Answer: D) Moving Explanation: In physics, we know that the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Hence, An object that has kinetic energy must be in motion i.e, moving.

Answer: D) Bauxite Explanation:

A line is an undefined term because of it :   1. Contains an infinite number of points 2. can be used to create other geometric shapes 3. is a term that does not have a formal definition   In Geometry, unless it's stated, a line will extend in one dimension and goes on forever in both ways.

Answer: B) +ve Explanation: We know the Mathematical rules that   ++ = ++- = --+ = --- = +

Answer: A) Repetitious Explanation: Here the given words, sullen and moody are synonyms to each other which means that gloomy, resentful. Similarly, repetitious and monotonous are synonyms to each other which means dull, tedious.   Hence, Sullen : moody :: monotonous : repetitious.

Answer: A) 84 km/hr Explanation: Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively.Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr.Also, 6x = 72 => x = 12 km/hrTherefore, the average speed of the car and train together is = 5x+9x2= 7x = 7 x 12 = 84 km/hr.

Answer: B) 9 kms Explanation: The first train covers 180 kms in 5 hrs => Speed = 180/5 = 36 kmph Now the second train covers the same distance in 1 hour less than the first train => 4 hrs => Speed of the second train = 180/4 = 45 kmph Now, required difference in distance in 1 hour = 45 - 36 = 9 kms.