Question Discussion & Solution

Hence, he is moving in north direction now.

The correct answer is Open Cast Mining.

• Open Cast Mining is the process under which minerals are mined near the earth's surface.

Key Points

• Opencast mining is the process that involves the removal of ore from seams relatively near the surface by means of an open-pit.
• These mines occupy a large area of land for excavation of the ore and disposal of the overburden.

Additional Information

• Drilling is a cutting process which uses a drill bit to cut a hole of circular cross-section in solid materials or ground.
• Quarrying is the process of removing rock, sand, gravel or minerals from the ground in order to use them to produce materials for construction or other uses.
• Shaft mining is the process where miners dig straight down until they reach their desired depth. 

The correct answer is 4°C.

• Freezing of Water:
  • As water freezes, cold water (or ice formed) comes on the surface and warm water goes down.
  • Since the freezing temperature of the water is 0ºC or 273 K.
  • So water at the bottom should be at a higher temperature.
  • Water density at 4ºC is more than the density of water at 0ºC, hence the correct option is 4ºC.

​Key Points

• Reason of low temperature at bottom of the top layer:
  • This is due to the process of convection.
  • When the temperature of the water at the top layer reaches the freezing point, it is converted to ice.
  • But ice is lighter than water, so it will not sink to the bottom.
  • So there will be ice on the top surface and water would remain at the bottom of the lake. 

The sound that Elephant makes is called a Trumpet.

Similarly,

the sound that Horse make is called Neigh.

Hence, Horse is related to “Neigh”.

Additional Information 

Some important animal sounds:

Here, all except Nohkalikai are names of different diseases while ‘Nohkalikai’ is a waterfall in India.