Questions

Ans.  Suppose the speed of boat in still water is x km/h and speed of stream is y km/h

Speedof boat in downstream = (x + y) km/h x+ y = 32 …(i) 

Speed of boat in upstream = (x – y) km/h

x – y = 28 …(ii)

Add. Eqs. (i) and (ii), we get 2x = 60

x = 30 km/h

Harappan or Indus Valley Civilization was the first and ancient civilization which started in what now Pakistan and North West India.

The Harappan civilization existed between 3300 BC and 1300 BC.

The ruins of Mohenjo-daro is a major archaeological site that was built by this civilization and is now a UNESCO World Heritage Site.

Here the letter 'M' appears once in Minute and twice in a MoMent.

Answer: U

Explanation:   Starting on the left, and moving along the line to the right, letters follow the alphabetic sequence, in steps of 1,2,3 and then 4, before repeating the sequence.

Ammonia is a base. One adding ammonia to water,the resulting solution will become basic. pH of an alkaline solution is 7. So the pH will increase

Skimming is the removal of any material or particles that are floating on the surface. Hence, Removal of oil and grease from sewage - waste water is called as skimming.

Most organic compounds contain carbon and hydrogen.