A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

Find the hidden tiger in the given optical illusion ?

What do you think with the below Picture ?

Which number should replace the question mark?

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

What jumps when it walks and sits when it stands?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

I am an odd number. Take away a letter and I become even. What number am I?

By what process could you make a 'Tea-Table' into food?