Q: What organs are the main organs of the urinary system? Choices: - spleen - prostate - gall bladder - kidneys A:
kidneys

Q: The atom often (but not always) turns into a different what during the decay process? Choices: - concept - reaction - aspect - element A:
element

Q: Q: A major source of primary pollutants is the burning of oil and coal, which are types of what? Choices: - erosion fuels - renewable fuels - greenhouse gases - fossil fuels A:
A: fossil fuels

Question: Q: Why do sharks sense low levels of electricity? Choices: - to locate mates - to sleep - to reproduce - to locate prey A:
Answer: to locate prey

*Question*
Q: How many stars are in our solar system? Choices: - two - none - three - one A:
**Answer**
one

(Q).
Q: What is a combination of two or more substances in any proportions called? Choices: - Combination - structure - mix - mixture A:
(A).
mixture