If there is NO wind resistance, just plain math, this is the answer.
To get the answer you would divide 800 by 650.
800/650 = 1.230769231 (exactly)
That would translate to exactly <span>1 hour 13 minutes and 50 seconds </span>
Their valence electrons don't give them the ability to bond, they are also not in need to any electrons, since they won't get an octet soon.
K(eq) = concentration of products/concentration of reactant
= [Cu+2] / [Ag+]^2
Activity of pure solid and liquid is taken as 1.
Hence last option is correct.
Hope this helps, have a great day ahead!