76. Which of the following gases is responsible for the greenhouse effect?
a) Nitrogen
b) Oxygen
c) Carbon dioxide
d) Water vapor
Answer: c) Carbon dioxide
77. What is the name of the atmospheric layer that contains the highest concentration of air molecules?
a) Troposphere
b) Stratosphere
c) Mesosphere
d) Thermosphere
Answer: a) Troposphere
78. Which of the following is a common outdoor air pollutant that can cause respiratory problems and acid rain?
a) Carbon monoxide
b) Nitrogen dioxide
c) Sulfur dioxide
d) Methane
Answer: c) Sulfur dioxide
79. What is the name of the atmospheric layer where the temperature increases with altitude?
a) Troposphere
b) Stratosphere
c) Mesosphere
d) Thermosphere
Answer: b) Stratosphere