A plant is placed in a sealed greenhouse with a fixed supply of water soil and air After a year the plant weighs 5 kg more than at the start of the experiment and what weighs almost 5 kg less?

The plant would weigh 5 kg more due to the process of photosynthesis, where it converts carbon dioxide and water into glucose and oxygen. The carbon in the glucose comes from the carbon dioxide in the air, while the hydrogen comes from the water in the soil. The almost 5 kg less weight would be attributed to the oxygen released during photosynthesis, which is a byproduct of the process.