Question

Yash left a sandwich in his lunchbox over the weekend . When he opened the lunch box on Monday, he found a whitish , cotton - like growth on the surface of the bread .
1) what could have caused the change ?
a-yeast
b-virus
c-bacteria
d-bread mould
2)do you think the sandwich might have been edible had Yash kept it in the refrigerator over the weekend ? Why ?
3) what other features of the sandwich would help Yash decide whether or not the sandwich is fit to eat ?
4) Do you think some milkshake left in a glass on the table for a few days would undergo a similar change ? Why ?
5) What would have happened to the milkshake in the glass ?

Answer 1

1. Bread Mould
2. Yes, because the refrigerator would help to prevent bacteria to react with sandwich.
3. Yes, because it would smell awful.

Answer 2

1)  It should be a chemical change as the smell and appearance both changed here. Since it grows on bread so it should be a bread mould. Hence option (d) is correct.  

2)  Yes. It may be edible as at the low temperature of freeze, bread mould cannot grow.  

3)  Bad smell and appearance help to decide that the sandwich is not edible.  

4)  Yes. It will also smell badly and will become curdy.

5)  If milk will be left to the milkshake in the glass bacteria will produce in the milk that will change the appearance and smell of milk.