Which of the following crops is of Kharif season?

Given below are the names of four energy crops. Which one of them can be cultivated for ethanol?

Radioactivity is measured by

Satellites used for telecommunication relay are kept in a geostationary orbit. A satellite is said to be in such an orbit when:
1. The orbit is geosynchronous.
2. The orbit is circular.
3. The orbit lies in the plane of the Earth’s equator.
4. The orbit is at an altitude of 22,236 km.
Select the correct answer using the codes given below:

The 2004 Tsunami made people realize that mangroves can serve as a reliable safety hedge against coastal calamities. How do mangroves function as a safety hedge?

The formation of ozone hole in the Antarctic region has been a cause of concern. What could be the reason for the formation of this hole?

The jet aircrafts fly very easily and smoothly in the lower stratosphere. What could be the appropriate explanation?
1. There are no clouds or water vapour in the lower stratosphere.
2. There are no vertical winds in the lower stratosphere.
Which of the statements given above is/are correct in this context?

What is a zoom lens?

What is the difference between a CFL and an LED lamp?
1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material.
2. The average life span of a CFL is much longer than that of an LED lamp
3. A CFL is less energy-efficient as compared to an LED lamp.
Which of the statements given above is/are correct?

Which one of following reflects back more sunlight as compared to other three?