Answer:
coal as a fuel source led to the invention of the printing press i think
<span>1200 meters is less than 1 kilometer
</span>is false
answer:
standard units are the units we usually use to measure the weight, length or capacity of objects.
explanation:
- international system of units or SI units are standard units
- these units used for measuring quantities are accepted worldwide
- for example: kilogram is standard unit for mass, second is standard unit for measuring time
Answer:
total amount of fluoride 3.6 *10^6 g
Explanation:
we know that
volume of reservoir 
=![\pi* [\frac{4.70*10^2}{2}]^2 *14.2](https://tex.z-dn.net/?f=%5Cpi%2A%20%5B%5Cfrac%7B4.70%2A10%5E2%7D%7B2%7D%5D%5E2%20%2A14.2)
= 2.25*10^6 m^3
denso=ity of water = 1000 kg/m3
mass of water = 1000*2.25*10^6
= 2.25*10^9 kg = 2.25*10^12 g
fluoride 1.6 ppm
total amount of fluoride 
= 3.6 *10^6 g