Need help, please give detailed explaination Part 1: Which of the following chan

Question

Need help, please give detailed explaination

Part 1: Which of the following changes in an ideal gas will result in an increase in pressure?

(i) Increasing the speed of the molecules in the gas at fixed V and n.

(ii) Decreasing the number of molecules in the gas at fixed V and T.

(iii) Decreasing the volume of the gas at fixed T and n.

A. only i

B. only iii

C. i and iii

D. ii and iii

E. i, ii, and iii

Part 2: Consider a balloon at STP filled with air, which is 78% N2, 21% O2, and 1% Ar. Which of the following statements are correct:

i) All three gases have the same average kinetic energy. ii) All three gases have the same rms speed. iii) All three gases have the same partial pressures.

A. i only

B. ii only

C. iii only

D. i and iii only

E. ii and iii only

Explanation / Answer

1)
(i) Increasing the speed of the molecules in the gas at fixed V and n.
to increase speed, we need to increase T
P*V = n*R*T
this will increase P

(ii) Decreasing the number of molecules in the gas at fixed V and T.
n is decreasing
P*V = n*R*T
this will decrease P

(iii) Decreasing the volume of the gas at fixed T and n.
V is decreasing
P*V = n*R*T
this will increase P

Answer:
D. ii and iii

2)
i) All three gases have the same average kinetic energy.
since temperature is same for all gases
KE = 3/2*R*T
KE will be same for all

ii) All three gases have the same rms speed.
Vrms = sqrt (3*R*T/M)
since molar mass, M is different for all,
rms spped will be different for all

iii) All three gases have the same partial pressures.
number of moles of gases are different
hence their partial pressures will be different

Answer: A. i only

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