Answer:
0.348 moles Ar
Explanation:
You can determine the moles of argon (Ar) by multiplying the given mass by the atomic mass of argon. This number gives the mass in grams per 1 mole. It is important to arrange the conversion in a way that allows for the cancellation of units. The final answer should have 3 significant figures to match the sig figs of the given value (13.9 = 3 sig figs).
Atomic Mass (Ar): 39.948 g/mol
13.9 g Ar 1 mole
----------------- x ------------------ = 0.348 moles Ar
39.948 g
Answer:
Explanation:
The half life of a radioactive atom is the time taken for half of the radioactive nuclei to disintegrate. The shorter the half life, the faster a radioactive nuclei decays.
Half life is often expressed as:
Half life = 
Where λ is the decay constant.
mechanical waves are classified by how they move. there are two types of mechanical waves:transverse waves and longitudinal waves.
Answer : The correct option is, (4) 6.0 mol
Explanation :
The given balanced chemical equation is,

In this reaction, lead undergoes reduction and chromium undergoes oxidation.
Oxidation reaction : It is the reaction in which a substance looses its electrons. In this oxidation state increases.
Reduction reaction : It is the reaction in which a substance gains electrons. In this oxidation state decreases.
Half reactions of oxidation-reduction are :
Oxidation : 
Reduction : 
From the reduction reaction, we conclude that 6 moles of electrons gained by the 3 moles of lead ions.
Hence, the correct option is, (4) 6.0 mole
Answer:
-1.71 J/K
Explanation:
To solve this problem we use the formula
ΔS = n*ΔH/T
Where n is mol, ΔH is enthalpy and T is temperature.
ΔH and T are already given by the problem, so now we calculate n:
Molar Mass C₂H₅OH = 46 g/mol
2.71 g C₂H₅OH ÷ 46g/mol = 0.0589 mol
Now we calculate ΔS:
ΔS = 0.0589 mol * −4600 J/mol / 158.7 K
ΔS = -1.71 J/K