Answer is: because they were using simple chemical reactions to transform elements, but that is possible only with nuclear reactions, which in that time were not possible to conduct.
Nuclear reactions can produce new elements, because number of protons and neutrons is changed, lead and gold have different atomic and mass numbers.
The electrons of an atom participates in a chemical reaction, chemical reactions involve the rearrangement of electrons, because there is transfer, loss, gain and sharing of electrons in chemical reactions, new elements are not formed.
Answer : The final temperature of the copper is, 
Solution :
Formula used :

where,
Q = heat gained = 299 cal
m = mass of copper = 52 g
c = specific heat of copper =
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get the final temperature of copper.


Therefore, the final temperature of the copper is, 
Answer:
589.038 m/s
Explanation:
i dont know if did this right tho