Answer: A) a wave reflects upon itself Explanation: A standing wave also known as a stationary wave, is a wave in which its peaks or any other point on the wave do not move spatially. This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions. The most common cause of standing waves is the phenomenon of resonance, in which standing waves occur inside a resonator due to interference between waves reflected back and forth at the resonator's resonant frequency.   Hence, standing wave occurs when a wave reflects upon itself.

Answer: D) a, b & c follows Explanation: Keeping in mind the safety and convenience of passengers, both 'a' and 'b' follow. 'c' clearly suggests a remedy to the problem and hence it also follows.

Answer: C) Dhrupad Explanation:

Answer: B) 2 Explanation: A number is divisible by 9 only if the sum of the digits of the number is divisible by 9. Here 86236 = 8 + 6 + 2 + 3 + 6 = 25 We must add 2 to 25 to become 27 which is divisible by 9.

Footsteps.  Yes, as you walk forward, you will leave the footstep behind you.

Answer: C) 5% Explanation: Let 'R%' be the rate of interest From the given data, 25202400 = 1 + R10041 + R1003⇒1 + R100 = 6360⇒R = 5   Hence, the rate of interest R = 5% per annum.

Answer: A) 7 Explanation: As the work is sameM1D1 = M2D2 Here Let the number of men employed was M=> 11M = 7(M+4)=> 11M - 7M = 28=> M = 7

Answer: D) -19 Explanation: HCF of 210 and 55 is 5 Now, 210x5 + 55P = 5 => 1050 + 55P = 5 => 55P = -1045 => P = -1045/55 => P = -19.