The value of z is x(.20) = (.40)y
In questions like this one , you should first read the passage and then read the instructions. DO NOT read the alternatives. Then , with the information you got from the passage , try to awnser the question without looking at the alternatives. Now compare your awnser to the alternatives and eliminate the ones you are sure are wrong.
From the passage you learn that light pollution , caused by man-made lights , sometimes creates fogs and hazes that make the night sky look like a "dark sheet of paper".
If you compare what you understood from the passage to the alternatives , you ll realize that A) is the one that makes more sense and its more compatible with your awnser.
If you eliminated all alternatives you could but there still are 2 choices remaining and you are not sure which one it is , go back to the passage and try to find evidence for each alternative and try to eliminate one of the alternatives
AWNSER : A)
The Paleozoic Era is bracketed by two major events in earth's history. It began with an unexplained explosion in animal life and ended with the world's largest mass-extinction known to man. The causes of these great events are currently unknown and under debate.
The reason why iron oxide has more mass than the iron is because Iron oxide has oxygen atoms, and pure iron does not.
When iron rusts and forms iron oxide, the iron oxide has more mass than the iron. Which statement correctly explains this
observation?
(A)Iron oxide has oxygen atoms, and pure iron does not.
(B)The oxygen atoms in iron oxide have more mass than the iron atoms in pure iron.
(C)The iron atoms in iron oxide have more mass than pure iron.
(D)There are more iron atoms in iron oxide than in pure iron.
When a chemical reaction takes place, other atoms are combined with pure elements to form compounds. This addition of another atom (oxygen) after reaction makes iron oxide formed heavier than pure iron.
Iron oxide is a chemical substance formed when pure iron rusts. The formation of iron oxide is a chemical reaction.
Hence, the correct answer to the question is; the iron is heavier because Iron oxide has oxygen atoms, and pure iron does not.
Learn more: brainly.com/question/6284546
