The mole fraction of a gas in solution is related to partial pressure of the gas above the solution by Henry’s law.

Partial pressure  

If temperature is lowered, solubility of gases increases at a given pressure. Thus, KH increases with increase in temperature. It is due to this reason that aquatic species are more comfortable in cold water rather than in warm water.

Note: K_h (Henry’s law constant) is in pressure unit, hence we use relation, Concentration xK_H = Pressure

In this case, K_H has been given in the unit of mol/kg bar. Thus, solubility of 0₂ (or concentration) = K_H P_gas

Henry's law states that at a constant temperature, the solubility of a gas is directly proportional to the pressure of a gas.
In other words, The partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution.
p = K_Hx
K_H is the henry's law constant. 

Henry’s law constant is in the unit of pressure, hence we use relation

Let number of moles of nitrogen = n

(Since, is very small)

Volume of CO = 0 .0354 mL = 0 .0354 x 10^- 3 L

p = 1 atm, T = 273 K

At high altitudes, the partial pressure of oxygen is less than that at the ground level. This leads to the low concentration of O₂ in the blood and tissues of the people residing in hill areas. This produces weakness and loss of memory.
Symptoms of this conditions is known as ANOXIA. Thus, Statements I are correct but Statement II is the correct explanation of Statement I.

When a gas dissolves in H₂O, vapour pressure decreases. Hence, increase in pressure of C0₂ leads to increase in solubility. Hence, soft drink bottles are sealed under high pressure of C0₂.
Thus, both Statements I are II are correct but Statement II is not the correct explanation of Statement I.

(a) When divers breathe under high pressure, solubility of atmospheric gases in blood increases. When divers come at the surface, pressure gradually decreases. Gases (N₂ and 0₂) are released in the form of bubbles which blocks capillaries and creates a medical symptoms called bends which are painful and dangerous. To avoid bends as well as toxic effects of high concentration of nitrogen in the blood, the tanks used by divers are filled with air diluted with helium (11.7% He, 56.2% N₂ and 32.1% Og). Thus, both Statements I and II are correct and Statement II is the correct explanation of Statement I.

The correct answer is option B.

At a constant pressure K_H is inversely proportional to x therefore higher the K_H lower the solubility.
The increasing solubility order is:
He < N₂ < H₂ < O₂
 

At saturated solution stage equilibrium gets established among dissolution and crystallisation.

The correct answer is option  D
In a saturated solution, more solute cannot be dissolved at a given temperature.
This is because, the solute dissolves in a solvent because of space between particles of solvent but on continuous addition of solute, the space between the solvent particles gets fulfilled. Thus no more solute particle can dissolve in a solvent.

The correct answer is option A
Henry’s law is a gas law which states that the amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid when the temperature is kept constant. The constant of proportionality for this relationship is called Henry’s law constant (usually denoted by ‘kH‘). The mathematical formula of Henry’s law is given by:
P ∝ C (or) P = k_H.C
Where,
 

• ‘P’ denotes the partial pressure of the gas in the atmosphere above the liquid.

• ‘C’ denotes the concentration of the dissolved gas.

• ‘kH’ is the Henry’s law constant of the gas.

This law was formulated in the early 19th century by the English chemist William Henry. It can be noted that Henry's law constant can be expressed in two different ways. If the constant is defined in terms of solubility/pressure, it is referred to as the Henry’s law solubility constant (denoted by ‘H’). On the other hand, if the proportionality constant is defined in terms of pressure/solubility, it is called the Henry’s law volatility constant (denoted by ‘kH’).

The correct answer is option A

According to Henry's law, solubility of a gas in a liquid is directly proportional to pressure of gas.
PαX
P = K_HX
P = Partial pressure of gas
X = solubility of gas in liquid
KH = Henry's constant
KH depends only on the nature of gas, nature of liquid and temperature (T). As temperature increases, 'K_H' increases and 'X' decreases.

The correct answer is Option A
The higher the value of KH, the lower is the solubility of the gas in the liquid. Hence the order of increasing solubility of the gases will be Ar <  CO₂4< HCHO

The correct answer is option D
Henry's law states that at a constant temperature, the solubility of a gas is directly proportional to the pressure of the gas.
In other words, The partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution.
p=KH​ x
Here, KH​ is Henry's law constant.
Hence, the given statement is Henry's law.