Answer : The volume of stock solution needed are, 12.5 mL
Explanation :
Formula used :

where,
are the initial molarity and volume of copper (II) chloride.
are the final molarity and volume of stock solution of copper (II) chloride.
We are given:

Putting values in above equation, we get:

Hence, the volume of stock solution needed are, 12.5 mL
Ivan Pavlov is most known for demonstrating conditioned lreflex in dogs.
<h3>what is conditioned reflex?</h3>
Conditioned reflex is a reflex action which has been conditioned to occur even without the stimulus which produces the reflex.
Ivan Pavlov is known to demonstrate conditioned reflex in dogs.
In his experiment, he trained dogs to salivate at the sound of a bell even if food which is the stimulus that produces salvation was not present.
Learn more about conditioned reflex at: brainly.com/question/24968947
<span>J.j thomson a british physicist was the first to identify the electron in 1987</span>