First, we need to compute the mass of oxygen found in 100 grams of saltpeter:
mass of oxygen = 100 - (mass of potassium + mass of nitrogen)
= 100 - (38.67 + 13.86)
= 100 - 52.53
mass of oxygen in 100 grams saltpeter = 47.47 grams
Now, we can use cross multiplication to find the mass of oxygen in 328 grams saltpeter as follows:
mass of oxygen = (328 x 47.47) / 100 = 155.7016 grams
I’m pretty sure you add, multiply, subtract, & divide
We know that density = mass /volume
so
mass=volume*density
volume=mass/density
so c is wrong