Investigation on three slices of mango.

A group of students are carrying out an investigation on three slices of mango. The results are recorded as follows:



1) What is the investigation about?
....To show that preserved food can be kept for a longer time.

2) In the investigation above, what is
.....changed? The method of keeping the mangoes.
.....observed? The condition of the mango after some time.

3) Why does Y turn slimy after the fifth day?
.....Due to the presence of bacteria.

4) What is the method used to preserve
.....W? Pickling
.....X? Cooling