
The 2 in front of
in
is <u>Coefficient.</u>
_____________________________
The
after
in the same equation is <u>sub </u><u>script</u><u>.</u>
_____________________________
There are two atoms of
in 
_____________________________

Answer:
0.252 mol
Explanation:
<em>Given the following reaction: </em>
<em>Cu + 2 AgNO₃ → 2 Ag + Cu(NO₃)₂</em>
<em>How many moles of Ag will be produced from 16.0 g Cu, assuming AgNO3 is available in excess.</em>
First, we write the balanced equation.
Cu + 2 AgNO₃ → 2 Ag + Cu(NO₃)₂
We can establish the following relations.
- The molar mass of Cu is 63.55 g/mol.
- The molar ratio of Cu to Ag is 1:1.
The moles of Ag produced from 16.0 g of Cu are:

I believe the problem is just simply asking for us to convert the value from one unit to the other. This case from m^3 to km^3. From the SI units, we know 1 km is equal to 1000 m. We do as follows:
118 m^3 ( 1 km / 1000 m )^3 = 1.18 x 10^-7 km^3