Classify each of the following pure substances as an element or a compound. a. silicon (si) chipb. oxygen (o2)c. hydrogen peroxide (h2o2)d. rust (fe2o3)e. methane (ch4) in natural gas

Iknow #2 is d. i just need to know why

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

Use the drop-down menus to label each of the following changes p for physical change and c for chemical change. the substance changes to a new substance. the original substance can be recovered. the color changes. gas is produced and given off. the substance changes size, shape, or volume.