Answer:
A
Explanation:
To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element.
We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.
Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element.
The number of grams : 17.082 g
<h3>Further explanation</h3>
Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

Where
M = Molarity
n = Number of moles of solute
V = Volume of solution
453.9 mL of 0.237 M calcium acetate

MW Ca(C₂H₃OO)₂ : 158,17 g/mol

Hey there!
For SN1 mechanism; the activation barrier is the C-I bond energy which is broken in the first step of the reaction.
The activation barrier is : 56 kcal/ mol = 5.6 kcal/ mole ( nearest 0.1)
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