Solution:

"World War I" was named after after "World War II"

Solution:

If you build a house on the South Pole, all of its walls will face towards North.

Solution:

The integer with the special property is -1.

To test the property, let us subtract any digit from it, let's say 5.

-1 - 5 = -6

The succeeding digit of 5 is 6.

When (-6) is divided by 6, it is completely divided.

For all other numbers as well, this stands true.

Solution:

The three numbers are:
-3, -1 and 1.

Solution:

The sword could not have the words 'World War I' engraved on it. At that time, only one world war had taken place. No one knew that a second was to happen in future. Thus if it was engraved, the mention of the number was impossible.

Solution:

10 = 9.9999999... .
The proof is correct and the fact is for real. There is no error in it.

Solution:

12/27

Explanation:
This is really simple if you know the concept. You just have to increase the fraction by multiplying with a number. In that way, you will increase the numerator and you will be able to find the required fraction. Here, we are multiplying the numerator and denominator of both the numbers with 9. Now if you simplify, the number will remain the same and thus dont think we changed the fraction.

1/3 * 9/9 = 9/27
2/3 * 9/9 = 18/27

Its easy to find the one third fraction on the way now i.e. 12/27.

Solution:

4

Explanation:
Now if you go on calculating 2^300, you will lose so much time and it might not even be feasible to carry out so long of calculations. Thus we will make use of a trick here. We will calculate the remainder of each power of 2 till we come across a pattern.

2^1 divided by 4 leaves the remainder 2.
2^2 divided by 4 leaves the remainder 0.
2^3 divided by 4 leaves the remainder 0.
2^4 divided by 4 leaves the remainder 0.

You can see that all the following powers of two will be divisible by 4. Therefore the remainder when 2^300 is divided by 4 will be 0 only.

Solution:

This problem can be solved with algebra as well as logical reasoning. We are going to tell you how it is logically possible.

Be it any quantity that was present in the beginning and any liquid as well. We know that we have taken a spoonful from one glass and put it into another. Then, we have taken a spoonful from the other glass and put it into the first glass. So, at the end of it, the quantity of liquid in either glass remains same as it was in the beginning.

Therefore, we can conclude the fact that any amount of coke that is missing in the glass with coke will be present in the lemonade glass. Also, the same quantity of lemonade will be missing from the lemonade glass and will be present in the coke glass.

Solution:

Mississippi.

(For example, One Mississippi, Two Mississippi, and Three Mississippi etc.)