A mixture of helium, nitrogen and oxygen has a total pressure of 741 mmHg. The partial pressure of helium is 158 mmHg, and the partial pressure of nitrogen is 180 mmHg. What is the partial pressure (in mmHg) of oxygen in the mixture?

403 mmHg

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a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.