Gaseous State

Step 1: Concept
At high pressures deep under the sea, the solubility of gases in the blood increases according to Henry's Law.
Step 2: Problem with Nitrogen
Nitrogen is highly soluble in blood at high pressure. When a diver ascends rapidly, the dissolved nitrogen forms bubbles in the blood, leading to a painful and dangerous condition known as "the bends" or decompression sickness.
Step 3: Advantage of Helium
Helium is much less soluble in blood than nitrogen even at high pressures. This property makes it a safer diluent for oxygen in diving cylinders.
Step 4: Conclusion
Therefore, helium-oxygen mixtures are preferred to prevent decompression sickness.
Final Answer: (A)

Step 1: Understanding the Concept:
Deep sea divers use specialized gas mixtures to avoid the toxic effects of nitrogen under high pressure.

Step 2: Detailed Explanation:
At high pressure, nitrogen dissolves in the blood and can cause "the bends" (decompression sickness). Helium is used to dilute oxygen because it is less soluble in blood than nitrogen and has a much lower density, making breathing easier at depth. The common mixture is heliox (O + He).

Step 3: Final Answer:
Divers use a mixture of oxygen and helium, which corresponds to option (D).

Step 1: Understanding the Concept:
Kinetic theory gives average KE = .
Step 2: Detailed Explanation:
KE directly.
Step 3: Final Answer:
Directly proportional to temperature.

Step 1: Understanding the Concept:
Graham's law: .
Step 2: Detailed Explanation:

Step 3: Final Answer:
Ratio is 1:1.414.

Step 1: Understanding the Concept:
Ideal gas equation: , and .
Step 2: Detailed Explanation:

Step 3: Final Answer:
.