Photochemical smog is produced
A) when conditions for acid rain are at their peak.
B) when secondary pollutants are present.
C) only in industrial areas.
D) when sunlight transforms certain gasses and aerosols.
Question 2
Fog forms at humidity values less than 100 percent
A) because of a large concentration of condensation nuclei.
B) because of a relatively small concentration of condensation nuclei.
C) only over ocean areas.
D) only over inland swamps and stagnant water areas.