A) a gas mixture
B) a gas
I believe it should be when he arranged the elements by their atomic mass.
Answer: Metals are shiny and lustrous with a high density. They have very high melting and boiling points because metallic bonding is very strong, so the atoms are reluctant to break apart into a liquid or gas.
Explanation:
sorry for not answering in less than 1 minute
<span>2 KClO3(s) → 3 O2(g) + 2 KCl(s)
</span><span>Note: MnO2 (Manganese Dioxide) is not part of the reaction. A catalyst lowers the activation energy and increases both forward and reverse reactions at equal rates.
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molar mass of KClO3 = 122.5
Moles of KClO3 = 3.45 / 122.55 = 0.028
Moles of O2 produce =

= 0.042 moles
molar mass of O2 = 32
so, mass of O2 = 32 x 0.042 = 1.35 g