For the first one the answer is B. and the second one is D.
<u>Answer:</u> The density of gold in
is 
<u>Explanation:</u>
Density is defined as the ratio of mass of the object and volume of the object. Mathematically,

We are given:
Density of gold = 
Using conversion factors:
1 lb = 453.6 g
1 feet = 12 inches
1 inch = 2.54 cm
Converting given quantity into
, we get:

Hence, the density of gold in
is 
First, we need to convert the grams of gold into mole using the molar mass (molecular weight) of gold, and then into particles using avogadro's number (1 mol= 6.02 x 10^23)
molar mass of gold= 197 grams/ mole
100.0 grams (1 mole/ 197 grams) x (6.02 x 10^23 particles/ 1 mole) = 3.06 x 10^23