[Q]: Which nongaseous compound can be made from two elements that are gases at room temperature?
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[A]: water

[Q]: Which of these best defines communicable diseases?
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[A]: They are spread to others.

[Q]: An astronomer is studying two stars that are the same distance from Earth. Star X appears brighter than star Y. Which statement best explains this observation?
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[A]:
Star X is larger than star Y.