A laser beam has intensity of $4.0\times10^{14}\ \text{W/m}^2$. The amplitude of magnetic field associated with the beam is ______ T. (Take $\varepsilon_0=8.85\times10^{-12}\ \text{C}^2/\text{N m}^2$ and $c=3\times10^8\ \text{m/s}$)
Standard electrode potentials of Na, Ni, and Cl are given. Which one has the highest reducing power?
$\text{Cl}_{2}(g) + 2e^- \&\rightarrow 2\text{Cl}^- $
$\text{Ni}^{2+} + 2e^- \&\rightarrow \text{Ni}(s) $
$\text{Na}^+ + e^- \&\rightarrow \text{Na}(s) $