A number of possible explanations for why manhole covers are round include :   1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole. 2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening. 3. A round manhole cover is easily moved and rolled. 4. Human beings have a roughly circular cross-section. 5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well. 6. It’s easier to dig a circular hole.

Answer: A) 60 Explanation: Given letters are k, l, m, n, o = 5 number of letters to be in the words = 3 Total number of words that can be formed from these 5 letters taken 3 at a time without repetation of letters = 5P3 ways. ⇒ 5P3 = 5 x 4 x 3 = 60 words.

Answer: C) 34 cm Explanation: Let the side of the square be 's' cm   length of rectangle = (s+5) cm   breadth of rectangle = (s-3)cm   (s+5) (s-3) =    s2 - 5s - 3s - 15 = s2    2s = 15   Perimeter of rectangle = 2(L+B) = 2(s+5 + s–3) = 2(2s + 2)   = 2(15 + 2) = 34 cm

Answer: A) Protects lungs Explanation: When you breathe in air through your nose, it contains lots of tiny things, like dust, dirt, germs, and pollen. The air enters our body through the nose. However, before it enters the lungs, it must be heated and purified. Many dust particles that enter along with the air are removed in the nose by mucus and thus it protects lungs.

Answer: A) Amino acids Explanation: Proteins are long chains of Amino acids. That is in brief, Amino acids are the monomers of Proteins. Amino acids are compounds which contain both an amino group and a carboxylic group. Proteins are made up of 20 essential amino acids. Monomer means a small molecule of an organic substance i.e, building block in general.

Answer: A) Y Explanation: If you add all the terms of the LHS of equality, then the last letter of the sum written in words would give you the RHS. 1 + 1 + 1 + 1 = 4 = FOUR 2 + 2 + 2 + 2 = 8 = EIGHT 3 + 3 + 3 + 3 = 12 = TWELVE 4 + 4 + 4 + 4 = 16 = SIXTEEN   So, following the same pattern. 5 + 5 + 5 + 5 = 20 = TWENTY   That gives us our answer to 5 5 5 5 =  "Y".

Answer: A) 19th Augusrt Explanation:

Answer: C) 200 mts Explanation: Let the length of the train be 'L' mts let the speed of the train be 'S' m/s Given it crosses a pole in 10 sec=> L/S = 10 ......(1)Given it takes 20 sec (double of pole) to cross a platform of length 200 mts => (L + 200)/S = 20 => L/S + 200/S = 20 But from (1) L/S = 10 => 200/S = 20 - 10 => S = 20 m/s Then, from (1) => L = 10 x 20 = 200 mts. Hence, the length of the train = 200 mts.