Almost 99% of Earth's atmosphere is made up of two gases. What are the two gases and the percents of each? A)
21% oxygen and 78% nitrogen
B)
21% water vapor and 78% oxygen
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21% nitrogen and 78% oxygen
D)
21% carbon dioxide and 78% oxygen

The isotonic saline solution described in part a is connected to an unknown solution via a semipermeable membrane, the unknown solution level drops. based on this information, what can be said about these two solutions?

City a and city b had two different temperatures on a particular day. on that day, four times the temperature of city a was 8â° c more than 3 times the temperature of city b. the temperature of city a minus twice the temperature of city b was â’3â° c. what was the temperature of city a and city b on that day? city a was 5â° c, and city b was 4â° c. city a was 3â° c, and city b was â’1â° c. city a was 8â° c, and city b was â’3â° c. city a was 5â° c, and city b was â’5â° c.

Why does his teacher ask him to balance the equation by including the correct coefficient