Which chess piece do you think is the strongest (after the queen)?

Simply rook, in starting position of course.

howw can pawn promote in to amazon which can checkmate without other peice

I would say amazon its op

At lower elo level, I would say the piece which the person knows better and is more comfortable for him/her using it to checkmate the king in the endgame. However, in theory, the rook is the second strongest piece after queen.

knight

Where do i buy the certificate for amazon? How long do I get to promote it with the certificate?

IDK

It depends on the dynamics of the position. It's he who gets there "firstest with the mostest." -Nathan B. Forrest. Really not a fan. Kept fighting after the war.

Chess tier list based on the pieces:

1. queen

2. rook

3. bishop

4. king

5. knight

6. pawn

Sometimes the bishop could be at number 2 if it's a fianchetto bishop or something.

The weaker a player is, the more they tend to over-value Knights.

octopus

The most important piece after the queen is the pawn that is just about to convert to a queen 

From a purely move based philosophy the strongest piece is the rook.

It can cover the most squares and is most useful on open files. 

However, the strongest piece is different from the most valuable  piece.

The most valuable piece is always going to be the King. It has infinite value. Capture Him, and the game is over.

Or how about a bishop that can threaten checkmate forcing the opponent's king to move to only one 

Besides, that, valuable is different from strong. 

A rook can be strong and have a lot of potential but if it's in a corner doing nothing, it's not valuable in the game. 

Same with a queen. What's valuable about a queen if it's just locked up in the corner doing nothing to participate in defense or attacks?

A pawn threatening to promote to a queen is not only close to promoting, but tying up the defense on the other side! You opponent is effectively down a piece because he has to defend the pawn.

Or consider a bishop in a game that is in an open position. It's much more valuable than your opponent's bishop if all of your pawns are on the same color as his bishop. 

Or consider a knight in a closed position. Much more valuable than a bishop. 

Or how about a bishop that forces the opponent's king to one square which allows a fork of the king and queen from the knight? 

In conclusion. generally speaking, the rook is the strongest. More specifically, there is a difference between value of a piece in a specific situation and it's general strength. The king is always the most valuable but not the strongest. A pawn can be more valuable in certain situations that the queen. It's situation specific.

For me, the order of most strongest to least:

1. Rook
2. Knight(it has the ability to jump over pieces)
3. Pawn(promotion)
4. Bishop(can move on only square of one colour)
5. King(with limited moves but most important)

Knight of 

Ni? 

After the Queen? A Pawn is worth one, it advances down the board to promote: 1+9=10, then you double that cos this Queen is more dangerous in the ending: 10+10=20, and you add another 6 cos it often Mates : 20+6=26. Round that out and you get 30, followed closely by the Queen(9).