Solution:

The remaining time is 15 minutes.

Since, 1/5 part of the time you have spent is left, the total time is 6 parts.

The total time is 90 minutes. 1/6 of 90 = 15.

Therefore, 15 minutes are remaining.

Solution:

Albumen is white of an egg (many of you have must have guessed yolk, which is yellow).

Solution:

1262

Sequence is based on formula:
Next = (1st Number)^2 - (2nd number)

7 12 37 ? 9142

7^2 - 12 = 37
12^2 - 37 = 107
37^2 - 107 = 1262 (Answer)
102^2 - 1262 = 9142

Solution:

A Door

Solution:

Can be done as the image below.

Solution:

Because president lives in it.

Solution:

3 pounds

Explanation:
Since one-quarter of the iron block weighs three-quarter of a pound, the whole the iron block will weigh (3/4 * 4 pounds).

Solution:

The numbers that have been written over the calendar are:
12, 4, 8 and 3

A few numbers have been circled under particular months. The curious thing is that the numbers that have been written are the same number of corresponding months under which the dates have been marked.

What we can judge by the overall calendar is that the dates that have been marked may refer to the letters at that position in the month's name. In addition, the written numbers can be the position of those letters. Let's simplify below:

12th month is December
The number marked under December = 5
The fifth letter of December = M

4th month is April
The number marked under April = 4
The fourth letter of April = I

8th month is August
The number marked under August is 6
The sixth letter of August = T

3rd month is March
The numbers marked under March are 4 and 5
The fourth and fifth letter of March = C and H

When you combine the letters, you get the name as MITCH.
Therefore, Mitch is the killer.

Solution:

Can be found on the pic below.

Solution:

She was playing baseball.

Solution:

It's a clever trick teaser.
We should note that Christmas occurs after 51 weeks and 2 days as in a calendar year new year comes before Christmas.

Solution:

False.

Some flowers are used to make perfumes but lily are not the only type of flowers and so it is not necessarily true that lily makes perfumes.

Solution:

The timer of a microwave.

The timer of a microwave generally consists of 4 digits. First two digit for minutes and next two for seconds.
So,
99 indicates - 1 minute 39 seconds
100 indicates - 1 minutes (1:00)

Solution:

A quill cannot write even a single word. However the person holding the quill can use it to write as many words possible with the given amount of ink.

Solution:

The fastest or even the slowest rabbit can only run till the mid point into the given garden. After the mid point, it will actually be running out of the given garden.

Solution:

It is an easy task. You just have to give the last chocolate along with the basket. That way, all gets a chocolate and the last one remains in the basket as well.

Solution:

It can be done as shown in the picture below.

Solution:

We are deck Of Cards

Solution:

John Walters was drowned in the quicksand.

Solution:

It can be done in image below.