Answer
$(b)$ metal $1$ has a smaller work function then metal $2$ has.
Work Step by Step
Wavelength is same for both metal $1$ and $2$ means energy is same for both the metals.
An we know:
$E$ $=$ $1/2mv^2$ $+$ $\phi$
Energy $=$ kinetic energy $+$ work function
First , energy is required to come out the electron from the bulk to the surface of metal and that energy is work function , second energy is required to remove the electron with maximum velocity from the surface of metal and that energy is kinetic energy.
In case of metal $1$ , energy is sufficient to come out the electron on the surface of metal from the bulk and that is not in case of metal $2$ .
That's why we can say that metal $1$ has smaller work function then that of metal $2$ .
