Photosynthesis is an endothermic chemical reaction that forms sugars from carbon dioxide, water, and the sun's energy. which of the following must be true of photosynthesis? the reaction can take place only if energy is added. the reactants are oxidized. the photosynthesis reaction produces ions. the molecular bonds in carbon dioxide are very weak.

The reaction can take place only if energy is added.

Explanation:

Exothermic processes are those processes in which heat is released and endothermic processes are those processes in which heat is absorbed.

Photosynthesis is a phenomenon in which green plants containing chlorophyll use sunlight as a source of energy to convert carbon dioxide and water to form glucose and oxygen.

Photosynthesis is the process used by plants, algae and certain bacteria to convert energy from sunlight and turn it into chemical energy in the form of glucose which is used a s a source of energy by many organisms.

Thus photosyynthesis reaction can take place only if energy is added.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.