Please help I really need it

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?

Solve each quadratic equation by factoring and using the zero product property. x^2 - 8x + 30 = 3x

Which of the following circles have their centers on the x-axis? check all that apply.