Select the statements below that are false and think about why they are not true.

a) If a chemical reaction is spontaneous then the ?Ssys must always be positive.

b)If a chemical reaction with a negative ?Ssys is spontaneous then ?Ssurr must be positive.

c) If a chemical reaction is spontaneous then the ?Euniv must be increasing.

d) We don\'t need to worry about spontaneous reactions because they are rare.

a) and d) are false.

Explanation:

a) The second law of thermodynamics states that the entropy of the universe increases in a spon taneous  process and remains unchanged in an equilibrium process.

For a spontaneous process:

ΔSuniv = ΔSsys + ΔSsurr > 0

For a spontaneous process, the second law says that ΔSuniv must be greater than  zero, but it does not place a restriction on either ΔSsys or ΔSsurr. Thus, it is possible  for either ΔSsys or ΔSsurr to be negative, as long as the sum of these two quantities  is greater than zero.

d) A  reaction that does occur under the given set of conditions is called a spontaneous  reaction. We observe spontaneous physical and chemical processes every day,  including many of the following examples:

• A waterfall runs downhill, but never up, spontaneously.

• A lump of sugar spontaneously dissolves in a cup of coffee, but dissolved sugar  does not spontaneously reappear in its original form.

• Heat flows from a hotter object to a colder one, but the reverse never happens  spontaneously.

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.

the answer is 75.0%.