The unknown substance : Lead
<h3>Further explanation</h3>
Given
Density of element
mass of unknown substance = 40 g
volume = 3.5 cm³
Required
The density of unknown substance
Solution
Density is the ratio of mass per unit volume
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:

Input the value to find the density of an unknown substance :
ρ = 40 g : 3.5 cm³
ρ = 11.43 g/cm³
If we look at the table, the substance which has a density of 11.43 is Lead
The correct answer is A, Water is not used up during this process. This is because when cellular respiration occurs oxygen and glucose combine. When this takes place water is left behind when carbon is separated from glucose. Because water is being left behind it is not being used up in this process.
your answer is c. two atoms of oxygen.