Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.

Correct Option: D

Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.

Like any other equilibrium constant, the value of Kw varies with temperature. Its value is usually taken to be 1.00 × 10^–14 mol² dm^–6 or Mol² lit^–2 at room temperature. In fact, this is its value at a bit less than 25°C. At 250 C, Kw = 1.00 x 10^–14 (mol/L)².

Correct Option: B

Like any other equilibrium constant, the value of Kw varies with temperature. Its value is usually taken to be 1.00 × 10^–14 mol² dm^–6 or Mol² lit^–2 at room temperature. In fact, this is its value at a bit less than 25°C. At 250 C, Kw = 1.00 x 10^–14 (mol/L)².

When sulphur pollutants fall on to buildings made from limestone and sandstone they react with minerals in the stone to form a powdery substance that can be washed away by rain. This is known as acid rain. Famous buildings like the Statue of Liberty in New York, the Taj Mahal in India and St. Paul's Cathedral in London have all been damaged by this sort of air pollution.

Correct Option: B

When sulphur pollutants fall on to buildings made from limestone and sandstone they react with minerals in the stone to form a powdery substance that can be washed away by rain. This is known as acid rain. Famous buildings like the Statue of Liberty in New York, the Taj Mahal in India and St. Paul's Cathedral in London have all been damaged by this sort of air pollution.

Spirit is very volatile. So when it is exposed, it evaporates rapidly to the air if released into the environment, producing a cool effect.

Correct Option: C

Spirit is very volatile. So when it is exposed, it evaporates rapidly to the air if released into the environment, producing a cool effect.

A heavy, silvery d-block element, Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine. With a freezing point of -38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.

Correct Option: B

A heavy, silvery d-block element, Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine. With a freezing point of -38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.