How can you tell a raw egg from a hard-boiled egg?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

What has a ring but no finger?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

What can you catch but never throw?

If an electric train is travelling south, then which way is the smoke going?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

What has 88 keys?

What does a man do only once in his lifetime, but women do once a year after they are 29?

A man is looking at a photograph of someone. His friend asks who it is. The man replies, “Brothers and sisters, I have none. But that man’s father is my father’s son.” Who was in the photograph?