He diagram below represents part of the oxygen cycle. Which arrow, or series of arrows, represent the movement of atmospheric oxygen (O2 ) during respiration?
a. only arrow 2 b. only arrows 2 and 6 c. only arrows 1 and 6 d. only arrow 6

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Which of these expressions are correct variations of the combined gas law? p1v1t2 = p2v2t1 both

Which element is least likely to undergo a chemical reaction