The carbon isotope used for the study of photosynthesis is ........

Variegated leaves of a plant were supplied with radioactive carbon dioxide $(^{14}CO_2)$ during an experiment. Leaf $X$ was kept in the dark and leaf $Y$ was kept in the light. At the end of the experiment,the radioactivity in the leaves was measured and found to be as shown in the diagram. What is the most likely explanation for the level of radioactivity found in the yellow zone of leaf $Y$?

Which scientist performed the experiment where a burning candle and a mouse were placed in a closed bell jar to demonstrate the role of air in the growth of plants?

When did the research on photosynthesis begin?

The scientist who proved that bacteria use $H_2S$ gas and $CO_2$ to synthesize carbohydrates is

The oxygen released during photosynthesis comes from..........