Root mean square velocity question

[Insiya]

If at 120 K the Vrms is v , then at 480 K it will be

a. 1
b. 2
c. 3
d. 4
Which formula is to be used here? Plz solve this.

 

[voko]

We don't solve anything here. We can help, but only if you show some effort.

 

[Insiya]

Ok.. but I couldn't understand it.. The formula mentioned in my book is Vrms= radical 3P/density so...What to do next?

 

[voko]

Are you saying there is no equation linking r. m. s. velocity and temperature that you know of?

 

[Insiya]

No.. I am not saying this.. This formula also shows relation with temperature but how to continue..?

 

[voko]

Perhaps you could express how pressure depends on temperature?

 

[Insiya]

Pressure has direct relation with temperature

 

[voko]

What is the equation?

 

[Insiya]

PV=nRT

 

[voko]

Use this and the equation given for r. m. s. velocity to relate the latter with T.

 

[Insiya]

Any clue?

 

[voko]

The clue is in #10. The rest is just algebra.

 

[Insiya]

ok.. Thank U