<span>First we can calculate the area of the rectangular lawn using the formula:
Area = Width x Length = 21 ft x 20 ft = 420 square feet
And the total number of snow flakes per minute on the entire lawn is:
(1350 snowflakes per minute per square foot) x (420 square feet) = 567,000 snowflakes per minute
In one hour (or 60 minutes) we get a total of:
(567,000 snowflakes per minute) x (60 minutes / 1 hour) = 34,020,000 snowflakes
The total mass of which would be:
34,020,000 snowflakes x 1.60 mg = 54,432,000 mg = 54.432 kg (as 1 kg = 1,000,000 mg).
So 54.432 kg of snow accumulates every hour on the lawn.</span>
Answer:
Density of the He atom = 12.69 g/cm³
Explanation:
From the information given:
Since 1 mole of an atom = 6.022x 10²³ atoms)
1 atom of He = 

The volume can be determined as folows:
since the diameter of the He atom is approximately 0.10 nm
the radius of the He =
= 0.05 nm
Converting it into cm, we have:


Assuming that it is a sphere, the volume of a sphere is
= 
= 
= 
Finally, the density can be calcuated by using the formula :


D = 12.69 g/cm³
Density of the He atom = 12.69 g/cm³
The molecular structure of the solids has lower ability to conduct electricity due to tight holding by nucleus.
<h3>Why molecular solids are poor conductors?</h3>
Molecular solids are also poor conductors of electricity because their valence electrons are tightly held by the nuclear charges present in the nucleus while on the other hand, Metals are good electrical conductors in the solid form due to the presence of free electrons that helps in the conduction of electricity.
Learn more about electricity here: brainly.com/question/25144822