It is D because nitrate reacts with the calcium and since na has a 2+ charge and no3 has a - charge we need 2 no3 to balance out the charge hence a 2 is placed outside the no3 bracket.
It can be an element or a compound
Answer:
A.
Explanation:
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The oxidation number for S in the compound SO3 is +6 (option D). Details about oxidation number can be found below.
<h3>What is oxidation number?</h3>
Oxidation number of an element is the hypothetical charge of an atom within a molecule.
The oxidation number of elements in a compound adds up to the overall charge of that compound.
According to this question, O has an oxidation number of -2 in SO3, the oxidation number of S can be calculated as follows:
x - 2(3) = 0
x - 6 = 0
x = 6
Therefore, the oxidation number for S in the compound SO3 is +6.
Learn more about oxidation number at: brainly.com/question/15167411
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Answer:
five half lives
Explanation:
Half-life is the time required for a quantity to reduce to half of its initial value.
How many half lives it would take to reach 3.13% form 100% of it's initial concentration:
100% - 50% : First Half life
50% - 25%: Second Half life
25% - 12.5%: Third Half life
12.5% - 6.25%: Fourth Half life
6.25% - 3.125%: Fifth Half life
This means it would take five half lives to get to 3.125% (≈ 3.13%) of it's original concentration.