B the atomic number is 20 and then you subtract atomic mass to find the neutrons
Answer:
The answer is letter A. Diamond
Explanation:
The diamond is a crystalline form of carbon, with a cubic structure, of the sp³ type, that is, each carbon atom of the structure is linked to four other carbon atoms, forming a tetrahedral geometry.
The average speed is calculated using the following formula
Where

T = 298 K [room temperature]
m = mass of each molecule of oxygen
mass of one mole of oxygen molecules = 32 g / mol
mass of one molecule of oxygen will be = 
mass of one molecule of oxygen will be = 
putting values
average speed = 
Average speed = 482.19 m / s
average speed = 1735.8 km / h
so approx = 1700 km/h