<u>Answer:</u> The volume of concentrated hydrochloric acid required is 16.53 mL
<u>Explanation:</u>
To calculate the volume of concentrated solution, we use the equation:

where,
are the molarity and volume of the concentrated solution
are the molarity and volume of diluted solution
We are given:
Conversion factor: 1 L = 1000 mL

Putting values in above equation, we get:

Hence, the volume of concentrated hydrochloric acid required is 16.53 mL
<h2>
Hello!</h2>
The answer is:
The empirical formula is the option B. 
<h2>
Why?</h2>
The empirical formula of a compound is the simplest formula that can be written. On the opposite, the molecular formula involves a variant of the same compound, but it can be also simplified to an empirical formula.

We are looking for a formula that cannot be simplified by dividing the number of molecules/atoms that conforms the compound.
Let's discard option by option in order to find which formula is an empirical formula (cannot be simplified)
A. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

B. 
It's an empirical formula since it cannot be obtained by the multiplication of a whole number and the simplest formula. It's the simplest formula that we can find of the compound.
C. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

D. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

Hence, the empirical formula is the option B. 
Have a nice day!
The answer is letter a. Hill terrain, hill slope, and hill elevation
Sr3(PO4)2 is definitely Ionic