# By what factor does the average velocity of a gaseous molecule increase when the temperature (in kelvin) is doubled ?

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By what factor does the average velocity of a gaseous molecule increase when the the temperature (in kelvin) is doubled ?

(1) 2.8

(2) 4.0

(3) 1.4

(4) 2.0

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Ans (3): 1.4

Sol: $V α \sqrt T$

temp is doubled

${V_1\over V}=\sqrt{T_1\over T}$

${V_1\over V}=\sqrt{2T\over T}$

${V_1\over V}=\sqrt2$

${V_1\over V}= 1.4$