An unknown substance is obtained by police. The forensics laboratory has determined it is made of nitrogen and oxygen. If 74.66 grams are nitrogen
and the police obtained a 250 gram sample, what is the percent
composition of oxygen in the sample?

70.0 %

Explanation:

Step 1: Given data

Step 2: Calculate the mass of oxygen (mO) in the compound

The mass of the compound is equal to the sum of the masses of the elements that form it.

mNxOy = mN + mO

mO = mNxOy - mN

mO = 250 g - 74.66 g = 175 g

Step 3: Determine the percent composition of oxygen in the sample

We will use the following expression.

%O = mO / mNxOy × 100%

%O = 175 g / 250 g × 100% = 70.0 %

specific gravity is the density of a substance divided by the density of water. since (at standard temperature and pressure) water has a density of 1 gram/cm3, and since all of the units cancel, specific gravity is usually very close to the same value as density

so "c" is the answer

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1.43 x 10^-11 j the guy commented the awnser just making sure u see it .