Exams › JEE Main › Physics

Assuming ideal gas behaviour, what is the ratio of the density of ammonia (NH3) to the density of helium (He) at the same temperature and pressure?

1. 1.64
2. 0.42
3. 4.25
4. 5.4

Correct answer: 4.25

Solution

Density ratio = M(NH3) / M(He) = 17 / 4 = 4.25. At the same T and P, density is directly proportional to molar mass for ideal gases.

Related JEE Main Physics questions

• Two gases A and B have their P vs V isotherms shown at the same temperature T. The critical temperatures of A and B are T_A and T_B respectively. From the graph, gas A shows a liquid-gas phase transition loop (below critical temperature) while gas B shows a smooth hyperbolic isotherm (above critical temperature). Which statements are correct? (I) The pressure correction term is more negligible for gas B at temperature T. (II) The P-V curve for gas B will have the same shape as gas A if T > T_B. (III) Gas A will show the same P-V curve as gas B if T > T_A.
• For a van der Waals real gas, the ratio PVm/(RT) at the temperature where (dP/dVm)_T = 0 (the critical temperature) equals x/24. Find the value of 10x.
• A 4-litre container holds 3 L of liquid water and O2 gas above it. The total gas pressure (O2 + water vapour) is 720 mm Hg. The container is connected to an initially empty 3-litre container at the same temperature. Find the final partial pressure of O2(g). [Vapour pressure of water at 27 deg C = 20 mm Hg]
• A 4:1 molar mixture of helium (He) and methane (CH4) is kept in a vessel at 20 bar pressure. Due to a small hole in the vessel, the gas mixture leaks out. What is the molar composition of the gas mixture effusing out initially?
• At the critical point of a van der Waals gas, the compressibility factor Z = P_c * V_c / (R * T_c) equals:
• A rigid closed container of volume 8.21 L holds 4 mol N2 and 6 mol O2 at 400 K (R = 0.0821 L·atm/(mol·K)). Which of the following statements are correct?

⚔️ Practice JEE Main Physics free + battle 1v1 →