Hey there!
Ninety nine percent of the atmosphere is composed of oxygen and nitrogen! The atmosphere is composed of 78% nitrogen and 21% oxygen!
Hope it helps :D
<u>Answer:</u> The density of substance is 
<u>Explanation:</u>
To calculate density of a substance, we use the equation:

We are given:
Mass of substance = 61.6 g
Volume of substance = 
Putting values in above equation, we get:

Hence, the density of substance is 
A food web is a system of interlocking and interdependent food chains.
A food chain is a hierarchical series of organisms each dependent on the next as a source of food.
Basically, the difference of the two is that a food web contains multiple different species in the same level that eat the animal below it's status. A food chain is one after the other.
<span>Stoichiometry deals with the quantitative measurement of reactants and products in a chemical reaction. Let suppose you are given with following reaction;
A + 2 B </span>→ 3 C
According to this reaction 1 mole of A reacts with 2 moles of B to produce 3 moles of C. Now using the concept of mole one can easily measure the amount of reactants reacted and the amount of product formed, as...
1 Mole Exactly equals 6.022 × 10²³ particles
1 Mole of Gas (at STP) exactly occupies 22.4 L Volume
1 Mole of any compound exactly equals the molar mass in grams
Therefore, <span>Stoichiometry is very helpful in quantitative analysis.</span>