Answer:
The percentage (by mass) of KBr in the original mixture was 33.1%.
Explanation:
The mixture of KCl and KBr has a mass of 3.595g, thus the sum of the moles of KCl (<em>x</em>) multiplied by it molar mass (74.5g/mol) and the moles of KBr (<em>y</em>) multiplied by it molar mass (119g/mol) is the total mass of the mixture:

Also, after the conversion of KBr into KCl, the total mass of 3.129 g is only from KCl moles, hence

But the 0.042 moles came from the originals KCl and KBr moles, thus

Now it is possible to propose a system of equations:


Solving the system of equations,

0.010 moles of KBr multiplied it molar mass is

Therefore, the percentage (by mass) of KBr in the original mixture was:
%
Not sure as don't know ratios, I think it could be 45.93g but don't take my word for it, it could be wrong.
The equations you need are moles = concentration x volume
and mass = moles x formula mass
Answer:
Extinction
Explanation:
When a species becomes extinct, every last specimen has died out
Answer:
Bases (solutions with a high pH) feel slipper, have an -OH group, and are corrosive.