Question

A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?

Answer 1

b<>Hint: The cement when reacts with water, it gets hardened and set in the shape it is present. If due to rain, the cement bag has been wet, then the cement will react with water and will get hardened. This reaction is irreversible in nature and can not be reversed back.

Complete step by step solution:
This type of question is related to science. But in case if one has not studied science from books, then also one with the daily observation of things surrounding us can answer this question.
The cement is a binding substance. It is an adhesive that is used to bind hard things. The cement that is used in buildings is called Portland cement. Chemically, its is made up of four main components that are tricalcium silicate ($3CaO \cdot Si{O_2}$), dicalcium silicate ($2CaO \cdot Si{O_2}$), tricalcium aluminate ($3CaO \cdot A{l_2}{O_3}$) and a tetra- calcium alumino ferrite ($4CaO \cdot A{l_2}{O_3}F{e_2}{O_3}$).
When the cement combines with water, the setting and hardening action results. This hardening can not be reversed. It is an irreversible process.
So, when the bag of cement lies open during the night. It got wet and the water reacted with cement forming a hard product. After exposure to the sun for not only one day, but even after many days, this hardening can not be overcome. It is an irreversible change.
What if such a change is irreversible. If such a change would have been reversible, then we have to protect our buildings every time from the sun. The sun would have reversed the hardened cement in buildings leading to their destruction.

So, this change is irreversible.

Note: It must be noted that cement is an adhesive material that is used for binding. The specific name for the cement that is used in buildings and other construction work is portland cement. It is used in the manufacture of bricks, tiles, shingles, railroad ties and many other things. These products are prefabricated and they are supplied such that they could be directly used.