I was wondering the same thing my dude
Yes cells are the blank unit for all things that are living
To calculate percent composition, you first need to find the molar mass of C (carbon), H (hydrogen) and O (oxygen).
C is 12.01
H is 1.00
O is 16
Then multiply each by the number of atoms of each element in the formula (the number that comes after each element in the equation for example C6 means 6 carbon atoms.
C: 12.01 x 6= 72.06
H: 1x12= 12
O: 16x6= 96
Then add them up.
72.06+ 12+ 96= 180.06
Now find the percent composition of carbon.
72.06/ 180.06 x 100= 40.01%
So the answer is C 40%.
From Melting! Hope this helped
2 hydrogen and 2 chlorine on the reactant side(left of the arrow)
There is only 1 H and 1Cl on the products side so the balanced equation would be;
H2 + Cl2 —> 2 HCl