Why is a finely divided particle layer of $Pt$ and $Pd$ provided on the electrodes of a fuel cell?

In an electrochemical cell,

Arrange the following metals in the order in which they displace each other from the solution of their salts: $Al$,$Cu$,$Fe$,$Mg$,and $Zn$.

Assertion : If $\lambda^o_{Na^{+}}$ and $\lambda^o_{Cl^{-}}$ are molar limiting conductivity of sodium and chloride ions respectively,then the limiting molar conductivity for sodium chloride is given by the equation :
$\Lambda^o_{NaCl} = \lambda^o_{Na^{+}} + \lambda^o_{Cl^{-}}$
Reason : This is according to Kohlrausch law of independent migration of ions.

$A$ secondary cell is one that:

Fill in the blanks :
$1$. Standard potential of Daniell cell is $\dots$ volt.
$2$. In Daniell cell,chemical energy is converted into $\dots$ energy.
$3$. In Daniell cell,$\dots$ is anode and $\dots$ is cathode.