Answer: 1- Option (D)
2- Option (A)
Step-by-step explanation:
The green house gases plays a significant role in the earth's global temperature. In absence of green house gas, the earth would have been very much cold and life would would be difficult to exist. The average global temperature would have been about -15°C to 25°C. So the most favorable answer given here is that the earth's temperature would have decrease by about 60°C.
Carbon dioxide (CO₂) is not the most abundant green house gas. It is the second most abundant. The present composition of CO₂ in the atmosphere is about 0.04% by volume. A small increase in the CO₂ level, can lead to a global rise in the temperature. Hence, the above statement is false.