Which is a physical change? cooking pancakes making toast burning wood melting chocolate

Enzymes affect the reactions in living cells by changing the

Consider the following reaction at equilibrium. 2co2 (g) 2co (g) + o2 (g) h° = -514 kj le châtelier's principle predicts that the equilibrium partial pressure of co (g) can be maximized by carrying out the reaction a. at high temperature and high pressure b. at high temperature and low pressure c. at low temperature and low pressure d. at low temperature and high pressure e. in the presence of solid carbon

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.