Which one of the following is the correct relation between A and nm?

The relationship between a nanometer (nm) and an angstrom (Å or A) is derived from their respective definitions in meters. A nanometer is defined as one billionth of a meter (10⁻⁹ m), while an angstrom is defined as one ten-billionth of a meter (10⁻¹⁰ m). Mathematically, since 10⁻⁹ m is ten times larger than 10⁻¹⁰ m, one nanometer contains exactly ten angstroms. To convert from nanometers to angstroms, one must multiply the value by 10. Conversely, one angstrom is equivalent to 0.1 nanometers. This conversion is fundamental in atomic physics and crystallography, where dimensions are often expressed at the scale of atoms and molecules. Therefore, the correct relation is 1 nm = 10 A.

Sources

1. [1] https://en.wikipedia.org/wiki/Angstrom