Solution:

8

Explanation:
If you look carefully then you will see that five matches lay ahead of the lighter and five are visible in the reflection of the lighter. Out of those five, we can see three matches emerging away from the surface of the lighter but two remains just as a part of reflection. Thus the total number of matches are eight.

Solution:

We now have a square of 3x3 size, 2 squares of 2x2 size and 5 squares of 1x1 size.

Solution:

The two numbers are 4 and 13 whose product is 52 and sum is 17.

Solution:

It can surely be true because it is not mentioned that it was raining.

Solution:

The clerk said that every day the password is CHANGED. Changed is the password.

Solution:

8/(1−1/5)

Solution:

What is the correct time ?

Solution:

The woman told him to take out one nut each from the rest of the wheels and use them.

Solution:

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

Solution:

Tilt the barrel until the fruit juice barely touches the lip of the barrel. If the bottom of the barrel is visible then it is less than half full.If the barrel bottom is still completely covered by the fruit juice, then it is more than half full.

Solution:

Set the first switches on for abt 10min, and then switch on the second switch and then enter the room.
Three cases are possible
1.Bulb is on => second switch is the ans
2.Bulb is off and on touching bulb , you will find bulb to be warm
=>1st switch is the ans.
3.Bulb is off and on touching second bulb , you will find bulb to be normal(not warm)
=>3rd bulb is the ans.