This is the correct option as azotobacter plays the role of nitrogen fixation in nitrogen cycle.

Pseudomonas converts nitrate salts into free nitrogen gas in nitrogen cycle. This process is known as denitrification.

Yes, it is correct. The solid form of water means snow, glaciers and ice. This can be seen on the hills and the highest of mountains, which are present at the poles.

Yes, it is correct as water vapour in the atmosphere condenses to form clouds. It takes place in the atmosphere and not on the land.

This is the correct option as all of the above are the harmful effects of ozone depletion on human beings, animals, plants and environment. This is the correct option as all of the above are harmful effects of ozone depletion on human beings, animals, plants and environment.

This is the correct option as nitrosomonas play the role of nitrification in the nitrogen cycle, i.e. convert ammonia into nitrites and then into nitrates.

Carbon gets included into the life-forms through the basic process of photosynthesis that takes place in the presence of sunlight.

Carbon is released into the atmosphere in several ways such as: Respiration, Decay of animal and plant matter, Burning of fossil fuels such as coal, petroleum products and natural gas, Production of cement, Volcanic eruptions and Metamorphism. Volcanic gases are primarily water vapour, carbon dioxide and sulphur dioxide, etc.  Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight.

Oxygen is necessary for every form of life and processes which they perform. But, some forms of life, especially bacteria, are poisoned by elemental oxygen. For example, the process of nitrogen fixation by nitrogen-fixing bacteria also takes place in the absence of oxygen and slows down in the presence of oxygen.

Oxygen is poisonous for anaerobic organisms as they work in the absence of oxygen.

This is the only advantageous application of greenhouse effect.

 Ozone is a potent respiratory hazard and pollutant near ground level. The ozone layer (a portion of the stratosphere with a higher concentration of ozone, from two to eight ppm) is beneficial, preventing damaging ultraviolet light from reaching the Earth's surface, to the benefit of both plants and animals.  

Oxygen from the atmosphere is used up in three processes, namely combustion, respiration and in the formation of oxides of nitrogen. Oxygen is returned to the atmosphere in only one major process, i.e. photosynthesis. 

The process of releasing surplus water into the air by plants is called transpiration. The process of changing of water into its vapours is called evaporation, while changing of water vapours into water is called condensation. The journey of water from oceans to atmosphere and back to oceans is called water cycle.

Limestone is a form of carbon and is present in oceans and seas.