I need help on 14-17
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Answer is: beryllium-10.
The diagram shows that atom has 4 protons, 5 neutrons and 2 valence electrons.
Atomic number is the number of protons, which is characteristic of a chemical element, beryllium (Be) is an element with atomic number 4.
Two valence electrons means that atom is from 2. group of periodic table, only beryllium is from that group; sodium (1. group), boron (13. group) and carbon (14. group).
Beryllium-10 has 6 neutrons, so it is isotope (different number of neutrons or mass number).
Answer : The volume of 4.9 M stock solution used to prepare the solution is, 12.24 ml
Solution : Given,
Molarity of aqueous solution = 1.20 M = 1.20 mole/L
Volume of aqueous solution = 50.0 ml = 0.05 L
(1 L = 1000 ml)
Molarity of stock solution = 4.9 M = 4.9 mole/L
Formula used :
where,
= Molarity of aqueous
solution
= Molarity of
stock solution
= Volume of aqueous
solution
= Volume of
stock solution
Now put all the given values in this formula, we get the volume of stock solution.
By rearranging the term, we get
Therefore, the volume of 4.9 M stock solution used to prepare the solution is, 12.24 ml