D! It’s a pure substance and a compound
Answer:first D. 88L
Second A 2*10^24
Explanation:
At stp 1 mole = 22.4L
mw Cl2= 70.9
280 g =280/70.9 moles, about 4
4*22.4 = about 88
aw Sr 87.6 —> 6.02214076*10^23 atoms = 1 mole
The moles of gas in the bottle has been 0.021 mol.
The ideal gas has been given as the gas where there has been negligible amount of interatomic collisions. The ideal gas equation has been given as:

<h3>Computation for the moles of gas</h3>
The gi<em>ve</em>n gas has standard pressure, 
The volume of the gas has been, 
The temperature of the gas has been, 
Substituting the values for the moles of gas, <em>n:</em>
<em />
<em />
The moles of gas in the bottle has been 0.021 mol.
Learn more about ideal gas, here:
brainly.com/question/8711877
Answer:
see notes below
Explanation:
The mole is the mass of substance containing 1 Avogadro's Number of particles. That is, 1 mole substance = 1 formula weight. For elements, 1 mole weight is equal to the atomic weight expressed as grams. For molecules, 1 mole weight is equal to the molecular weight expressed as grams.
1 mole = 1 formula weight
<u>Moles to Grams and Grams to Moles</u>
Grams => Moles
Given grams, moles = mass given / formula weight
*Ask the question => How many formula weights are there in the given mass? => Results is always moles.
Moles => Grams
Given moles, grams = moles given X formula weight
*Summary
Grams to Moles => divide by formula weight
Moles to Grams => multiply by formula weight