What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

What word is represented by this rebus?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

I have branches, but no fruit, trunk or leaves. What am I?

Find the missing letter in the last circle logically in the given below picture.

In a boat, the father of a sailor's son is sitting with the son of the sailor. However, the sailor is not present on the boat.

Can this even be possible?

Find the next number in the sequence

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

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.