500 millimeters equals how many liters?

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

The ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?

If (x-2) 2= 49, then x could be a. -9 b. -7 c.- 2 d. 5 e.9