Because of the way the question was worded, it was clear that the fifth president, James Monroe, was one of them. Otherwise, the trivia question would have been “among the first four US presidents” instead of “among the first five”. Since the three presidents that died on fourth of July were consecutive ones, they were Jefferson, Madison, and Monroe.

The solutions are shown below.

You should say “I will receive a chocolate”. This statement cannot be correct, since if it was, you would get a lollipop or a chewing gum, not a chocolate. Therefore, you will get the car.

The solutions are shown below.
demolish, moderate, delicate
nihilist, holistic, historic

The solution is shown below:

Nine matchsticks are enough, as seen from the solution below.
To see that eight matchsticks are not enough, notice that removing an inner matchstick reduces the number of 1×1 squares at most by 2. Since there are 16 such small squares, in order to get rid of them all, we need to remove only inner matchsticks. However, in this case, the large 4×4 square will remain.

The solutions are shown below.

The solution is shown below:

Since there are 8 rows on the chess board, if you place more than 16 pawns, then there will be at least 3 that lie on a single horizontal line. An example with 16 pawns is shown below:

You can place 6 X’s without getting 3 X’s on a line, as shown below.
If you place 7 X’s on the board, since 3×2<7, at least one of the rows (and also one of the columns) will have 3 X’s.