12 x 10^23 atoms, i hope this helps
Dmitri Mendeleev
<span> Dmitri Mendeleev and Lothar Meyer individually came up with their own periodic law "when the elements are arranged in order of increasing atomic mass,
certain sets of properties recur periodically.</span>
Explanation:
firstly find for the molar mass of kcl and molar mass of k
and then
molar mass of k = x
molar mass of kcl= 40
cross mutiply and then simplify you will get your answer