How can you remove the hard calcium carbonate layer of the egg without damaging its semi - permeable membrane ? Can this egg be inserted into a bottle with a narrow neck without distorting its shape ? Explain the process involved.

Explanation

(i) When egg is placed in dilute mineral acid solution (preferably dilute HCl solution), the hard external `CaCO_(3)` layer of the egg dissolves out / removed without damaging its semi - permeable membrane.
(ii) Yes, this egg can be inserted into a bottle with a narrow neck without distorting is shape. The process involved utilising phenomenon of osmosis is explained as below - Egg is placed in mineral acid solution - after some time egg is removed and placed in a hypertonic solution * - size of the egg gradually decreases after some time and it shrivels due to osmosis. Since the egg has shrivelled it can, now be inserted easily into a bottle with narrow mouth. The egg is, therefore, placed in a bottle with narrow neck & then a hypotonic solution is filled into this bottle. On adding hypotonic solution **, egg regains shape due to osmosis.
Hypertonic solution - is a solution with higher salt concentration than that of the normal body cells so that the solvent / water is drawn out of the cell by osmosis , or any solution with higher osmotic pressure than another solution is called ..Hypertonic solution...

Hypotonic solution is a solution with lower salt concentration than that of the normal body cells so that water / colvent flows into the cell by osmosis, or - hypotonic solutions a solution which has lower osmotic pressure than the other solution.