Correct question
The density of liquid mercury is 13.6 g/mL. What is its density in units of lb/in3? (2.5 cm = 1 in., 2.205 lbs= 1 kg., 1000 g =1 kg, 1 mL = 1 cm³)
Answer:

Explanation:
Given that;-
The density = 13.6 g/mL
Also, 1 kg = 2.205 lb
1 kg = 1000 g
So, 1000 g = 2.205 lb
1 g = 0.002205 lb
Also,
1 in = 2.54 cm
1 in³ = 16.39 cm³
1 cm³ = 1 mL
So, 1 in³ = 16.39 mL
1 mL = 0.061 in³
The expression for the calculation of density is shown below as:-

Thus,

Explanation:
Methane molecule is depicted here
<span>1.15x10^24 molecules of hypothetical substance b
Making the assumption that each molecule in hypothetical substance a reacts to produce a single molecule of hypothetical substance b, then the number of molecules of substance b will be the number of moles of substance a multiplied by avogadro's number. So
Moles hypothetical substance a = 29.9 g / 15.7 g/mol = 1.904458599 moles
This means that we should also have 1.904458599 moles of hypothetical substance b. And to get the number of atoms, multiply by 6.0221409x10^23, so:
1.904458599 * 6.0221409x10^23 = 1.146892x10^24 molecules.
Rounding to 3 significant figures gives 1.15x10^24</span>
Answer:
Explanation:
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a. the distance light travels in one earth year