Landscapes will undergo the most chemical weathering if the climate is

warm and wet

Explanation:

Chemical weathering is the erosion and disintegration of the rocks and earth materials caused by the chemical reaction that takes place on them by the action of geologic agents like winds, water, and ice. The process responsible for the chemical weathering is oxidation, hydration, hydrolysis, and carbonization of the rocks.  This the most favorable conditions for the chemical weathering to take place occurs in those areas which have plenty of moisture and humid conditions. Thus the tropics are the place that experiences most of the chemical weathering process as compared to the temperatures and the polar regions of the earth.   As tropics remain wet most time of the year, the wetness weakens the rocks thereby exposing them to these agents.

The answer for your problem would be a. 7

The answer to the first one is barometer.