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:
%
This is going to lead you to the element Argon. Is this what you are asking?
Answer:
A
Explanation:
heat energy is transfered through a hot object touching a cold object
Cocaine selectively blocks sodium channels which is the mechanism that leads to local anesthetic effects.
Voltage gated sodium channels play very important roles in the body as they are responsible for action initiation and propagation in excitable cells, such as nerves, muscles and neuroendocrine cells. Like other sodium ion channels blockers such as lidocaine, Cocaine selectively blocks sodium ion channels which denies entry of sodium ions in the cell, thus leading to local anesthetic effects.