Question

Water glass, utilized for preservation of shelled egg is a solution of

• A. Calcium oxide
• B. Calcium carbonate
• C. Sodium silicate
• D. Sodium chloride

Hint:

Water glass preservation is an inexpensive, traditional preservation method.
A typical dilution ratio of 1 part sodium silicate to 9 parts boiled and cooled water is used to keep eggs viable for up to 6 months.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Preserving shell eggs involves sealing the microscopic pores of the eggshell to prevent moisture loss, carbon dioxide escape, and the entry of spoilage-causing microorganisms.
Detailed Explanation:
"Water glass" is the common name for a concentrated aqueous solution of sodium silicate (\(Na_2SiO_3\)).
When shell eggs are submerged in a diluted solution of water glass, a chemical reaction occurs between the sodium silicate and the calcium carbonate of the eggshell.
This reaction deposits a fine, glassy silica precipitate over the shell, effectively sealing its microscopic pores.
By blocking these pores:
- Evaporation of water from the albumen is minimized, preserving egg weight and internal quality.
- The entry of atmospheric oxygen and environmental bacteria is prevented, slowing down biochemical degradation.
- The eggs can be kept relatively fresh for several months at room temperature.
Other options like calcium oxide, calcium carbonate, or sodium chloride do not possess the same pore-sealing properties when applied as a liquid coating.

Step 2: Final Answer:
Water glass used for egg preservation is a solution of sodium silicate.