OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www wisedane
OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www. wisedane. com
PHYSICS Kinetic Theory Of Gases SET 3 MCQ’S
Q 1. A container has N molecules at absolute temperature T. If the number of molecules is doubled but kinetic energy in the box remains the same as before, the absolute temperature of the gas is : A. T B. T/2 C. 2 T D. Zero
ANSWER (B) EXPLANATION
Q 2. Three closed vessels A, B and C are at the same temperature T and contain gases which obey the Maxwellian distribution of velocities. Vessel A contains only O 2, B only N 2 and C a mixture of equal quantities of O 2 and N 2. If the average speed of the O 2 molecules in vessel A is V 2. The average speed of the O 2 molecules in vessel C is : (Taking M as the mass of an oxygen molecule)
ANSWER (B) EXPLANATION Ø The average speed of the same type of molecules at the same temperature would be the same
ANSWER (D) EXPLANATION
ANSWER (B) EXPLANATION
A. Ne B. O 3 C. N 2 D. NH 3
ANSWER (B) EXPLANATION Ø On solving n = 6. It is triatomic gas molecule having triangular structure, i. e. , O 3.
Q 6. Two chambers containing m 1 and m 2 gram of a gas at pressures P 1 and P 2 respectively are put in communication with each other, temperature remaining constant. The common pressure reached will be :
ANSWER (A) EXPLANATION
Q 7. A gas is filled in a cylinder. Its temperature is increased by 20% on kelvin scale and volume is reduced to 90%. How much percentage of the gas has to leak for pressure to remain constant ? A. 20 % B. 25 % C. 30 % D. 40 %
ANSWER (B) EXPLANATION
Q 8. A gas in a vessel is at the pressure P 0. If the masses of all the molecules be made half and their speed be made double then the percentage increase in resultant pressure will be : A. 25% B. 50% C. 75% D. 100%
ANSWER (D) EXPLANATION
Q 9. The rms velocity of hydrogen molecule at 27 o. C is v. H and that of oxygen at 402 o. C is v 0, then v 0/v. H is : A. 4 B. 9/4 C. 13/9 D. 3/2
ANSWER (D) EXPLANATION
Q 10. The pressure of a gas kept in an isothermal container is 200 k Pa. If half of the gas is removed from it, the pressure will be : A. 100 k Pa B. 200 k Pa C. 141 k Pa D. 400 k Pa
ANSWER (A) EXPLANATION
Q 11. A tube of uniform area of cross section is closed at one end and open at other end. To enclose a column of air inside the tube a pellet of mercury is introduced. Figure shown, if the length of air column at 27 o. C is 9 cm. at what temperature its length will be 10. 5 cm ? A. 67 o. C B. 77 o. C C. 87 o. C D. 97 o. C
ANSWER (B) EXPLANATION Ø Here, pressure constant but volume and temp. of air change. Thus, Charle’s Law is obeyed. Ø Let A be the area of cross section of the tube. L 1, L 2, be the length of air column at temperatures T 1 and T 2 respectively. Then,
A. 500 B. 550 C. 575 D. 615
ANSWER (A) EXPLANATION Ø Let V be the final volume of balloon when filled with hydrogen. Then,
ANSWER (B) EXPLANATION Ø Energy acquired by electron when accelerated through a potential difference of 5 V
Q 14. 15 g of nitrogen is enclosed in a vessel at temperature 27 OC. The amount of heat required to double the rms velocity of these molecules is
ANSWER (B) EXPLANATION
A. 330 ms-1 B. 390 ms-1 C. 410 ms-1 D. 430 ms-1
ANSWER (C) EXPLANATION
Q 16. The rms speed of oxygen molecule at 827 o. C is 900 m/s. The rms speed of argon at 47 o. C is : [Molecular weight of oxygen is 32 and that of argon is 40] A. 225 m/s B. 339 m/s C. 433 m/s D. 439 m/s
ANSWER (D) EXPLANATION
ANSWER (C) EXPLANATION
ANSWER (d) EXPLANATION
A. 103 K B. 104 K C. 105 k D. 106 K
ANSWER (B) EXPLANATION
A. 0. 072 N/m 2 B. 7. 2 N/m 2 C. 72 N/m 2 D. 720 N/m 2
ANSWER (A) EXPLANATION
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