URGENT ILL MAKE YOU BRAINLIEST PLS

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?

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population,find the population standard deviation, o.79828588912497

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?