Answer:
145 grams of a 0.480 % KCN solution contains 697 mg of KCN.
Explanation:
w/w % : The percentage mass or fraction is mass of the of solute present in 100 grams of the solution.

given = w/w% = 0.480 %
Mass of solute that KCN = 697 mg = 0.697 g
(1 mg = 0.001 g)
Mass of the solution = ? = x


x = 145.21 g ≈ 145 g
145 grams of a 0.480 % KCN solution contains 697 mg of KCN.
Seeing signs of a chemical reaction does not always mean that a reaction is happening. For example, a gas (water vapor) is given off when water boils. ... You can tell that it is a physical change because water vapor can condense to form liquid water. In a chemical change, a new substance must be produced.
69.9%
Explanation:
To find the mass percentage of iron in the compound in Fe₂O₃, we would go ahead to express the given molar mass of the iron to that of the compound.
Mass percentage =
x 100
Molar mass of Fe = 55.85g/mol
Molar mass of O = 16g/mol
Molar mass of Fe₂O₃ = 2(55.85) + 3(16) = 159.7g/mol
Mass percentage =
= 69.94% = 69.9%
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I would say D. Let me know if i am wrong.