7,500 expressed in scientific notation

7.5 x 10³

Explanation:

The positive exponent means that the decimal place was moved the left and the exponent itself tells you how many places it moved.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.