I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

Name a key which is hardest to turn.

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

Decode this picture on T-Shirt and tell what it says ?

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?