Aluminum can react with oxygen gas to produce aluminum oxide (Al2O3). What type of reaction is this? A. single replacement
2 answers:
Answer: B. combustion
Explanation:
A. Single replacement: A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.
B. Combustion: is a chemical reaction between a substance and an oxidant usually atmospheric oxygen accompanied by generation of heat and light.
C. Double replacement: A double replacement reaction is one in which exchange of ions take place.
D. Decomposition : is a reaction in which one reactant decomposes to give two or more than two products.
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Answer : The molecular weight of a substance is 157.3 g/mol
Explanation :
As we are given that 7 % by weight that means 7 grams of solute present in 100 grams of solution.
Mass of solute = 7 g
Mass of solution = 100 g
Mass of solvent = 100 - 7 = 93 g
Formula used :
where,
= change in freezing point
= temperature of pure water =
= temperature of solution =
= freezing point constant of water =
m = molality
Now put all the given values in this formula, we get
Therefore, the molecular weight of a substance is 157.3 g/mol