Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Nuclear changes occur with a simultaneous release of energy. Where does this energy come from? If we could precisely measure the masses of the reactants and the products of a nuclear reaction, we would notice that the amount of mass drops slightly in the conversion from reactants to products. Consider the following nuclear reaction, in which the molar mass of each species is indicated to four decimal places:. Answer: energy
[EX A]: Nuclear changes occur with a simultaneous release of what, and a slight drop in mass?

[EX Q]: Passage: The convection zone surrounds the radiative zone. In the convection zone, hot material from near the Sun's center rises. This material cools at the surface, and then plunges back downward. The material then receives more heat from the radiative zone. Answer: convection zone
[EX A]: Hot material from near the sun's center rises in which zone?

[EX Q]: Passage: The epidermis is the outer layer of skin, consisting of epithelial cells and little else (see Figure below ). For example, there are no nerve endings or blood vessels in the epidermis. The innermost cells of the epidermis are continuously dividing through mitosis to form new cells. The newly formed cells move up through the epidermis toward the skin surface, while producing a tough, fibrous protein called keratin. The cells become filled with keratin and die by the time they reach the surface, where they form a protective, waterproof layer called the stratum corneum. The dead cells are gradually shed from the surface of the skin and replaced by other cells. Answer: epidermis
[EX A]:
What is the outer layer of skin, consisting almost entirely of epithelial cells?