A polished metallic piece and a black painted wooden piece are kept in open in bright sun for a long time.

When a potato piece is kept in a highly concentrated salt solution, then

A small piece of aluminium metal was placed in a beaker containing a greenish solution. After some time a grey coating was observed on the aluminium piece. The greenish solution is most likely to be:

A small cylindrical soft iron piece is kept in a galvanometer so that

A polished metal plate with a rough black spot on it is heated to about 1400K and quickly taken into dark room Then .

A piece of charcol and a piece of shining steel of the same surface area are kept for a long time in an open lawn in bright sun.

A piece of string is 40 centimeters long. It is cut into three pieces. The longest piece is 3 times as long as the middle- sized piece and the shortest piece is 23 centimeters shorter than the longest piece. Find the length of the shortest piece.

Silver articles turn black when kept in the open for longer time due to the formation of

A piece of metal is cut from a hollow metal sphere of radius R and is polished on both sides. A boy looks at the metal piece and finds his image 13 cm behind the metal piece. His friend flips the mirror, keeping its position unchanged and now the boy finds his image to be 52 cm behind the mirror. Find R.