Question 2: It is easier to burn the ingredients by stir-frying them with peanuts than by boiling them with water: it is because the boiling point of oil is higher than that of water;

Question 3: When the lid of the pot is lifted for a moment, the lenses become blurred right away: it is a phenomenon of liquefaction;

Question 4: the whole kitchen is filled with the fresh fragrance of radish rice: this phenomenon shows that molecules can be used in the cooking of radish rice. This phenomenon shows that the molecules are in constant irregular motion.

The answer is: atmospheric pressure; boiling point; liquefaction; the irregular motion of molecules.