A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

I have Rs.50 and I spend it in the way as below.

I am green and found in the forest and have needles instead of leaves. What am I?
Hint 1: It can be used for Christmas decorations.
Hint 2: I have a strong, scent that is used in air fresheners.

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Kareena is older than Katrina and younger than Karishma. Isabelle is younger than Bipasha and Karishma. Bipasha is older than Karishma. If Kareena and Isabelle are the same age, who's the youngest?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

The more of this there is, the less you see. What is it?