Why do we preferably have round manhole covers and not square ones?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?

Spot 5 differences in two Christmas tree below:

Three people are in a room. Ronni looks at the Nile. The Nile looks at Senthil. Ronni is married but Senthil is not married. At any point, is a married person looking at an unmarried person? Yes, No or Cannot be determined.

Can you write down eight eights so that they add up to one thousand?

A bomb exploded in a room full of married couples and no one died. How?

John: "Hi Teacher, What is your favourite movie ?".
Chemistry Teacher: "Indium Cerium Platinum Iodine Oxygen Nitrogen".
Ten seconds later... John replied I got it.

Do you?

A girl says this to her best friend: “I was born in 1955, and I celebrated my 17th birthday last weekend.” Her best friend thinks she’s lying, but she’s actually correct. How is that possible?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?