What is the number of the lowest energy level that contains an f sublevel?

n = 4.

Explanation:

1) The main energy level is represented by the principal (main) quantum number, n. It can be 1, 2, 3, 4, 5,6, or 7. It is the period number in the periodic table.

2) The next quantum number is the Azimuthal quantum number (ℓ), also known as angular quantum number. It indicates the subshell (sublevel) or type of orbital.

This quantun number may be:

s, p, d, or f.

3) For n = 1, there is only one ℓ number: 0; which is the orbital s

For n = 2, there are two possible ℓ numbers: 0 and 1; which are the orbitals s and p.

For n = 3, there are three possible ℓ numbers: 0, 1, and 2, which are the orbitals s, p, and d:

For n = 4, there are four possible ℓ numbers:0, 1, 2, and 3; which are the orbitals s, p, d, and f.

So, the f sublevel appears first time when n = 4, i.e the number of the lowest energy level that contains an f sublevel is 4.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.