(a) True

Plant contains the stomata. Stomata are minute pores present on epidermics of leave and are meant for gaseous exchange (respiratory gasses) and transpiration. Oxygen and carbon dioxide enters into the plant through the stomata and are used in respiration and photosythesis.

(b) True

The amount of oxygen produced by the plant during photosynthesis is more than the amount of oxygen consume by the plant during respiration. Plant produce oxygen during photosynthesis and consume oxygen during respiration. Plant take the carbon dioxide through the leaves(stomata) and combined it with water and sunlight to form their food(glucose). During this process oxygen is also formed as a byproduct. Which is relased into the atmosphere.

(c) False

Air helps in the movements of sailing yachts and glider as well as it (air) also play an important role in the flight of birds and aeroplanes.

(d) False

Air occupies every space that is available to it. Air is everywhere.