Unit Cells

1. (1): Correct. Antibiotics are often products of microbial metabolism (e.g., penicillin from Penicillium species).
2. (2): Correct. Many antibiotics are synthetic analogues (e.g., sulfonamides).
3. (3): Correct. Antibiotics are effective at low concentrations due to their high specificity.
4. (4): Incorrect. Antibiotics inhibit the growth or kill microorganisms; they do not promote their survival.
Antibiotics are agents that inhibit the growth of or kill microorganisms. They do not promote survival and are effective at low concentrations.

In the CaCl structure:

• Ca²⁺ ions are located at the body center.
• Cl⁻ ions are present at the corners of the cubic unit cell.

Geometric Considerations:

The relationship between the ionic radii and edge length is derived as follows:

• The body diagonal of the cubic unit cell passes through the center of the unit cell, connecting opposite corners.
• The length of the body diagonal is given by , where is the edge length of the cube.
• In the CaCl structure, the body diagonal is equal to the sum of the diameters of the cation and anion:

Relationship:

Equating the body diagonal to :

Dividing by 2:

Final Formula:

The relationship between the ionic radii and edge length is: