When force is exerted over a distance ,work is done by force. Forces can be classified as conservative or non conservative. The work done by a non conservative force depends on the path over which the force acts. Friction is an example of a non conservative force because the amount of work that must be done to overcome friction depends on the path taken .consider a person pushing a crate across a warehouse floor as shown in the diagram Describe how the normal force changes as the mass of the crate increases.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

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

it's c (engineer's do their work with mechanical stuff not on any living being)