(Question)
Answer the following question given this paragraph: The strong nuclear force works only over very short distances. As a result, it isn't effective if the nucleus gets too big. As more protons are added to the nucleus, the electromagnetic force of repulsion between them gets stronger, while the strong nuclear force of attraction between them gets weaker. This puts an upper limit on the number of protons an atom can have and remain stable. If atoms have more than 83 protons, the electromagnetic repulsion between them is greater than the strong nuclear force of attraction between them. This makes the nucleus unstable, or radioactive, so it breaks down. The following video discusses the strong nuclear force and its role in the atom. The video also introduces the weak nuclear force, which is described next. Q: If the electromagnetic repulsion between protons is greater than the strong nuclear force of attraction between them, what do they become? Choices: - unstable , or experimental - slow , or radioactive - destroyed - unstable, or radioactive A:
(Answer)
unstable, or radioactive

(Question)
Answer the following question given this paragraph: Ingestive protists ingest, or engulf, bacteria and other small particles. They extend their cell wall and cell membrane around the food item, forming a food vacuole . Then enzymes digest the food in the vacuole. Q: Ingestive protists extend their cell wall and cell membrane around the food item, forming a what? Choices: - food pocket - fuel vacuole - protective bubble - food vacuole A:
(Answer)
food vacuole

(Question)
Answer the following question given this paragraph: Each muscle in the body is made up of cells called muscle fibers. Muscle fibers are long, thin cells that can do something that other cells cannot dothey are able to get shorter. Shortening of muscle fibers is called contraction . Muscle fibers can contract because they are made of proteins, called actin and myosin, that form long filaments (or fibers). When muscles contract, these protein filaments slide or glide past one another, shortening the length of the cell. When your muscles relax, the length extends back to the previous position. Nearly all movement in the body is the result of muscle contraction. Q: Shortening of muscle fibers is called what?' Choices: - diffusion - diffusion - shrinking - contraction A:
(Answer)
contraction