Answer: C) 15 July Explanation: World Population day is an annual event, observed on July 11 every year, which seeks to raise awareness of global population issues.

Answer: D) All the above Explanation:

Answer: D) Bogota Explanation:

Answer: A) 50 days Explanation: 50 men can build a tank in 40 days  Assume 1 man does 1 unit of work in 1 day Then the total work is 50×40 = 2000 units   50 men work in the first 10 days and completes 50×10 = 500 units of work 45 men work in the next 10 days and completes 45×10 = 450 units of work 40 men work in the next 10 days and completes 40×10 = 400 units of work 35 men work in the next 10 days and completes 35×10 = 350 units of work So far 500 + 450 + 400 + 350 = 1700 units of work is completed and   Remaining work is 2000 - 1700 = 300 units   30 men work in the next 10 days. In each day, they does 30 units of work.   Therefore, additional days required = 300/30 =10   Thus, total 10+10+10+10+10 = 50 days required.

Answer: B) Gasoline additive Explanation: Tetraethyl lead is a highly toxic compound used as a gasoline additive. Tetraethyl lead abbreviated as TEL, is an organo lead compound with the formula (CH3CH2)4Pb. It is a petro-fuel additive which in turn caused increased vehicle performance. This is also used as an antiknock agent in gasoline and jet fuels. Tetraethyl lead is absorbed rapidly by the skin, the lungs, and the gastrointestinal tract. It is converted to triethyl lead, which might be responsible for its toxicity.

Answer: C) 12 kmph Explanation: Let the distance traveled be x km.Then, x/10 - x/15 = 23x - 2x = 60 => x = 60 km.Time taken to travel 60 km at 10 km/hr = 60/10 = 6 hrs.So, Robert started 6 hours before 2. p.m. i.e., at 8 a.m.Required speed = 60/5 = 12 kmph.

Answer: D) Both A & B Explanation:

Answer: D) 2:1 Explanation: 5M + 2B = 4(1M + 1B) 5M + 2B = 4M + 4B 1M = 2B The required ratio of work done by a man and a boy = 2:1