First we must write a balanced chemical equation for this reaction

The mole ratio for the reaction between
and
is 1:2. This means 1 moles of
will neutralize 2 moles
. Now we find the moles of each reactant based on the mass and molar mass.



The
was enough to neutralize the acid because 18.87:39.67 is the same as 1:2 mol ratio.
From the information given:
- The volume of the graduated cylinder = 50.0 mL
- when a sterling silver pendant is added, the volume increases to = 61.3 mL
∴
The volume of the sterling silver pendant is:
= 61.3 mL - 50.0 mL
= 11.3 mL
Since, 1 mL = 1cm³
Then;
11.3 mL = 11.3 cm³
- the density of the sterling silver = 10.25 g/cm³
Using the relation for Density; i.e.


mass = 10.25 g/cm³× 11.3 cm³
mass of the sterling silver = 115.825 grams
Recall that sterling silver has:
- 92.5% silver and;
- 7.5% copper
∴
The mass of the copper contained in the sterling silver pendant can be calculated as:

= 8.687 grams
Therefore, we can conclude that the mass of the copper contained in the sterling silver pendant is 8.687 grams
Learn more about the relation between Density, Mass, and Volume here:
brainly.com/question/24386693?referrer=searchResults
////// it is pepsinogen //////
The answer is “Only some of the molecules of a weak base dissociate to produce hydroxide ions when mixed with water, but all of the molecules of a strong base dissociate to produce hydroxide ions”