392. One greenhouse gas contributes 14% to total global warming and another contributes 6%. These are respectively identified as

A. N2O and CO2
B. CFCs and N2O
C. Methane and CO2
D. Methane and CFCs
✅ The correct answer is option B.
One greenhouse gas contributes 14% to total global warming and another contributes 6%. These are respectively identified as CFCs and N2O.

397. The source of energy in an ecosystem is

A. ATP
B. Sunlight
C. D.N.A
D. R.N.A
✅ The correct answer is option B.
The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.

399. What is the man-made greenhouse gas known as?

A. Carbon dioxide
B. HFC
C. Ozone
D. Water Vapour
✅ The correct answer is option B.
Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6).

400. In the Northern Hemisphere, this day has the fewest hours of daylight:

A. Summer solstice
B. Winter solstice
C. Vernal equinox
D. Autumnal equinox
✅ The correct answer is option B.
For people in the Northern Hemisphere, the December solstice marks the exact opposite, the day of the year with fewest hours of daylight. North of the Arctic Circle towards the North Pole there is no direct sunlight at all during this time of the year.