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

According to le chatelier’s principle, a system in chemical equilibrium responds to stress by shifting the equilibrium in a direction that reduces the stress. normalizes the stress. increases the stress. changes the stress.

One similarity and one difference between an element and a mixture of elements

1) a light bulb takes in 30 of energy per second. it transfers 3j as use energy. calculate the efficiency. second. it transfers 3j as useful light energy and 27j as heat energy. calculate the efficiency