What will happen to the rate of photosynthesis in a plant under the following circumstances?
$(i)$ Cloudy day in the morning but bright sunshine in the afternoon.
(ii) No rainfall in the area for a considerable time.
(iii) Gathering of dust on the leaves.

(N/A) $(i)$ The rate of photosynthesis decreases in the morning due to low light intensity but increases in the afternoon as light intensity rises.
(ii) The rate of photosynthesis decreases because water is a raw material for photosynthesis and its scarcity leads to the closure of stomata, reducing $CO_2$ intake.
(iii) The rate of photosynthesis decreases because dust blocks sunlight and clogs stomata, hindering gas exchange.