Doreen Schmidt is a chemist. She needs to prepare 28 ounces of a 12% hydrochloric acid solution. Find the amount of 14% solution and the amount of 7% solution she should mix to get this solution.

20 ounces of 14% solution and 8 ounces of 7% solution.

Explanation:

Let the amount of 14% solution required be A and the amount of 7% solution required be B.

Mixture of A and B must give 28 ounces:

A + B = 28 Eqn 1

Also, mixture of 14% A and 7% B must give 12%, 28 ounces solution:

0.14A + 0.07B = 0.12(28) = 3.36Eqn 2

From eqn 1, B = 28 - A, eqn 2 becomes:

0.14A + 0.07(28 - A) = 3.36

0.07A = 3.36 - 1.96

A = 20 ounces

Substitute the value of A into eqn 1 to get B:

20 + B = 28

B = 8 ounces.

Hence, 20 ounces of 14% hydrochloric acid and 8 ounces of 7% hydrochoric acid should be mixed together in order to get 28 ounces of 12% solution.

the answer is the first option

explanation:

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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.