<u>Answer:</u> The number of moles of calcium metal required is 2.0 moles.
<u>Explanation:</u>
We are given:
Moles of water reacted = 4.0 moles
The given chemical reaction follows:

By Stoichiometry of the reaction:
2 moles of water is reacted with 1 mole of calcium metal
So, 4.0 moles of water will react with =
of calcium metal
Hence, the number of moles of calcium metal required is 2.0 moles.
Answer:
c) none of them
Explanation:
because H20, N2 , O2 are all molecules except NaCl so there is no answers like ( 1, 3, and4 ) so we choose none of them.
Answer:
C. Deductive reasoning
Explanation:
Deductive reasoning is a reasoning or logical process whereby a conclusion is drawn based on the belief of multiple premises that are generally assumed to be true. It is a logical process in which one or multiple statements reaches a logical conclusion.
In the question, the statement assumed to be true is that <em>noble gases are unreactive because of their electronic structures.</em>
The conclusion thus drawn from the premise is that <em>if other elements could be made to achieve noble gases electronic structures (</em><u><em>this is the reason why they are unreactive - the fact)</em></u><em> they would be more stable.</em>
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Therefore, deductive reasoning moves from a wilder reasoning to a specific (narrower) reasoning.
There are 2 significant figures.
"Rule 3: Trailing zeros are significant if a decimal point is shown in the number, but may or may not be significant if no decimal point is shown."
Answer:

Explanation:
Hello there!
In this case, for the given reactants side, we infer this is a double replacement reaction because all the cations and anions are switched around as a result of the chemical change, we infer that the products side include aluminum with nitrate and magnesium with sulfate as shown below:

However, we need to balance since unequal number of atoms are present at both sides, thus, we do that as shown below:

Thus, we make 6 Al atoms, 3 S atoms, 3 Mg atoms and 30 O atoms on each side in agreement with the law of conservation of mass.
Regards!