Answer: D) 96 Explanation: Here in the given number puzzle, the given numbers follows a pattern that  1 + 4 = 5 => 1 x 4 + 1 = 4 + 1 = 5  2 + 5 = 12 => 2 x 5 + 2 = 10 + 2 = 12    3 + 6 = 21 => 3 x 6 + 3 = 18 + 3 = 21  Similarly,  8 + 11 = 96 => 8 x 11 + 8 = 88 + 8 = 96   Hence, the missing number in the given number puzzle is 96.

Answer: B) Oxygen Explanation: Rust forms when oxygen reacts with chemicals in rocks, and that is often the case with many other elements in general. Like a copper nail being exposed to the air will rust.

The sound is what can you hear but not touch or see.

Answer: C) Afforestation Explanation: The four most common soil erosion prevention methods are vegetation, geotextiles, mulch, and retaining walls. By planting grass in areas of concentrated water flow, farmers can prevent much of the soil erosion that results from runoff, as the grass stabilizes the soil while still providing an outlet for drainage. Preventing soil erosion is critical in protecting your property and exposed soil, whether from wind, weather, running water, and even the after-effects of the forest fire.

Answer: C) 4 Explanation: N = H.C.F. of (4665 - 1305), (6905 - 4665) and (6905 - 1305) = H.C.F. of 3360, 2240 and 5600 = 1120. Sum of digits in N = ( 1 + 1 + 2 + 0 ) = 4

Answer: D) 140 mts Explanation: Speeds of two trains = 30 kmph and 58 kmph => Relative speed = 58 - 30 = 28 kmph = 28 x 5/18 m/s = 70/9 m/s Given a man takes time to cross length of faster train = 18 sec   Now, required Length of faster train = speed x time = 70/9  x  18 = 140 mts.

Answer: C) 71 Explanation: To find the greatest number which divides the numbers 964, 1238 and 1400 leaving the remainders 41, 31 and 51 is nothing but the HCF of (964 - 41), (1238 - 31), (1400 - 51). Therefore, HCF of 923, 1207 and 1349 is 71.

Answer: B) 3:2:4 Explanation: Given, y/(x - z) = (y + x)/z = x/yyz = xy + x2 - yz - xz ....(1)Also xy = yx-z ⇒x2 -xz = y2 ....(2)Using (1) and (2), we get yz = xy - yz + y22yz = xy + y22z = x + y Only option (B) satisfies the equation.