Question

The preservation of meat by salting and of fruits by adding sugar protects them from bacterial action because:
A.Bacterial die of eating sugar and salt
B.Due to osmosis bacteria lose water on salted meat or candid fruit die
C.Due to osmosis bacteria gain water on salted meat or candid fruit die
D.Bacteria get stuck to the salt and sugar layer and die.

Answer 1

Hint: The process involving in the preservation of food in the above question is based on one of the colligative properties. Due to movement of solvent the bacteria die.

Complete step by step answer:
The above question is based on the colligative property known as osmotic pressure. Osmotic pressure is that colligative property in which the solvent molecule moves from low concentration to the higher concentration through a semipermeable membrane. Semi permeable membrane is that membrane which allows movement of certain molecules only, especially the solvent molecules.
The movement of solvent molecules occurs. Since when the concentration of solution is high then the amount of solvent is less and when the concentration of solvent is low then the amount of solvent is high. So basically a solvent moves from their high concentration to lower concentration or from low concentrated solution to high concentrated solution.
Now whenever we add salt on to meat or sugar in fruits then if any bacterium is present, the osmosis occurs. The semipermeable membrane is present in animal cells. The outside of bacteria has little or no water but inside of bacteria there is more water. Water will flow from bacteria to the salt solution and hence they shrink and die. Similar thing occurs when sugar is added to the fruits.

Hence option B is correct.

Note:
Salt and sugar are very good natural preservatives. In jams, jellies excess of sugar is added to enhance taste as well as to preserve them from bacteria. Highly saturated solution of salt known as brine is also used as a preservative. A colligative property is that property which depends on the number of moles of solute.