nitrogen gas contained in a cylinder with a volume of 5.0x10^2 mL @ a temp of 30C and pressure of 710 torr. The gas is then compresse to a volume of 25mL and the temp. is reaised to 820C. what is the new pressure of the nitrogen gas??

Pf=p1*v1*t1/Tf*Vf

P=(700torr)(5.02x10^2mL)(820+273)K/(30+273)K(25mL)= 5.1x10^4 torr

please let me know if is correct and where i can find more prob. like this so i can practice.,..thankx :)

looks good to me.

A book like the Shaum's is pretty good. You may be able to find some practice problems on google. Just type in something like gas law problems.
http://chemistry.about.com/cs/workedproblems/a/bl113003a.htm

Your calculation is almost correct, but there seems to be a mistake in converting the temperatures to Kelvin. The correct equation to use is the Ideal Gas Law equation, which is:

P1 * V1 / T1 = P2 * V2 / T2

Where:
P1 = initial pressure (in torr)
V1 = initial volume (in mL)
T1 = initial temperature (in Kelvin)
P2 = final pressure (unknown)
V2 = final volume (in mL)
T2 = final temperature (in Kelvin)

Let's plug in the given values:

P1 = 710 torr
V1 = 5.0x10^2 mL
T1 = 30°C = 30 + 273 = 303 K
V2 = 25 mL
T2 = 820°C = 820 + 273 = 1093 K

Now we can solve for P2:

P2 = (P1 * V1 * T2) / (V2 * T1)
= (710 torr * 5.0x10^2 mL * 1093 K) / (25 mL * 303 K)
= 398,314 torr (rounded to the nearest whole number)

So the new pressure of the nitrogen gas is approximately 398,314 torr.

As for finding more practice problems like this, I recommend searching for thermodynamics or gas laws practice questions online. There are many educational websites and textbooks that provide practice problems. Additionally, you can check out online learning platforms such as Khan Academy or Coursera, which offer courses on thermodynamics and chemistry that may include practice problems.