In chemistry rusting is called as oxidation. Oxidation is a chemical process where metal gains oxygen and become oxide. In rusting the Iron ore make a chemical reaction with the oxygen in the presence of water and environmental or atmospheric moisture to produce an Iron oxide. Iron oxide is otherwise called as rust. The rusting of iron is a chemical change because it is two substances reacting together to make a new substance.    Rusting would only be a physical change if iron molecules remained pure iron throughout the process.

Answer: C) 1/6 Explanation: Given X can do in 10 days  => 1 day work of X = 1/10   Y can do in 15 days  => 1 day work of Y = 1/15   1day work of (X + Y) = 1/10 + 1/15 = 1/6   Given they are hired for 5 days  => 5 days work of (X + Y) = 5 x 1/6 = 5/6  Therefore, Unfinished work = 1 - 5/6 = 1/6

Answer: A) 5 kmph Explanation: Let p be the speed of man in kmph According to the given data in the question, Distance travelled by bus in 10 min with 20 kmph == Distance travelled by man in 8 min with (20 + p) kmph in opposite direction => 20 x 10/60 = 8/60 (20 + p) => 200 = 160 + 8p => p = 40/8 = 5 kmph.

Answer: B) 165 Explanation: The given series follow the rule that : Multiplying consecutive prime numbers2,3,5,7,11,13,17,19....2x3 = 63x5 = 155x7 = 357x11 = 7711x13 = 14313x17 = 221So, the wrong term is 165.

Answer: C) Rs. 500 Explanation: 110% of S.P. = Rs. 616 S.P. = (616 x 100)/110 = Rs. 560 C.P = (110 x 560)/112 = Rs. 500

Answer: D) 6011 hrs Explanation: From March 6th to November 11th, there are 250 days and Thus 250 x 24 hoursSo from Mar 6th 9AM to Nov 11th 8PM, there will be 250 x 24 + 11 hours = 6011 hrs.

Answer: D) 50 cub.m/min Explanation: Let filling capacity of the pump be 'F' m3/min Then, the filling capacity of the pump will be (F + 10) m3/min From the given data, 2400F - 2400F+10= 8⇒ 2400 F+10-FF(F+10) =8⇒ F2 + 10F - 3000 = 0⇒ F = 50 m3/min

Answer: D) 100 & 4 Explanation: Let the first number be x and the second number be y. Given 5% of x = (25% of y) + y => 5x/100 = 5y/4 => x = 25y ......(1) and also given that, x - y = 96 => x = 96 + y .....(2) From (1)&(2) 25y = 96 + y => 24y = 96 => y = 4 From (1) x = 96 + 4 = 100 Hence, the numbers are 100 & 4.