What Adam and Eve do not have but the rest of the people have?

what does the below math rebus puzzle mean?

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.

What country can make you shiver?

Rahul decided to meet Simran so he boards a local train from Bombay station. Just after the station, there is a 1km long tunnel. The train starts and is now accelerating. Rahul is a claustrophobic guy, so what is the best position for him to sit?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

John is pretty weird. He likes toffees but hates chocolates. He loves books but never reads. He likes to build his troops in an online game but does not proceed with the war. He likes to go swimming but is afraid of water.

Seeking this behaviour, can you tell whether he likes balloons and parties?

You have to put a letter on the following to make it a meaningful word. The only challenge is that you can't use 'E'.

S E Q U E N C _

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?