I have teeth but i don't bite. Who Am I ?

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

Find the number of squares in the below picture

How many letters are in the alphabet?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

A couple went on a climbing trip. But only the husband returned from the vacation and said that his wife slipped off while climbing and died. On investigating, the local sheriff arrested him saying, 'Your travel agent called. You murdered your wife.'

The man did not inform anyone about the trip. Then how was the agent so sure that it was a murder?

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

Find the next number in the sequence

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

Can you solve the photo plexer logic ?