The model below shows an atom of an element. 10 light gray and 8 dark gray balls sit at the center with 2 concentric black rings around them. the inner ring has 2 medium gray balls on it, and the outer ring has 6 medium gray balls on it. at bottom, a dark gray ball = +1, a light gray ball = 0, a medium gray ball = negative 1. what is the atomic number of this atom? a. 6 b. 8 c. 9 d. 16

The Atomic Number of the atom of an element whose model is given is "8" that is option no. 'C' in the question.

Explanation:

An Atom comprises of 3 basic structures that are Protons, Neutrons and Electrons. The central part is the Nucleus which contains protons and neutrons having positive charge and no charge respectively. The electrons are revolving around the nucleus in electronic shells having the negative charge.

ATOMIC NUMBER:

Atomic number is the number of protons present inside the nucleus of an atom and it determines the place of that particular atom in the Periodic Table.

In the model, given in the question, the nucleus contains 2 types of balls dark gray colored and light gray colored. The key at the bottom shows the dark gray colored ball as having a positive charge and thus it represents the atomic number for the given atom of element which is EIGHT (8).

So, the atomic number for the given atom is 8 which is element OXYGEN.  

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

they are all solids.