What does the sign represent with respect to electrons?

a. opposite spin of two electrons

b. different principal energy levels of two electrons

c. distances of two electrons from the nucleus

d. attraction between two electrons

the sign is an up arrow and a down arrow next to each other
the answer is a. opposite spin of two electrons

A. opposite spin of two electrons

Explanation:

Four quantum numbers identify electrons:

n - the principal number. It indicates the shell where the electron is, and it is from 1 to 7 and by the letters K, L, M, N, O, P, and Q.

l - the azimuthal number. It indicates the subshell where the electron is, and it varies from 0 to 3 and it is represented by the letters s, p, d, and f.

ml - the magnetic number. It represents the orbital where it is easy to find the electron. Each orbital supports two electrons, and it varies from -l to +l.

ms - the spin number. It represents the spin of the electron, which can be -1/2 or + 1/2. At the orbital, the electrons have different spins, which are represented by arrows, the up arrow represents the -1/2 and the down arrow the +1/2.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3