Which of the following is an amphoteric oxide?

$A$ Zener diode,having a breakdown voltage equal to $15\, V$,is used in a voltage regulator circuit as shown in the figure. The current through the Zener diode is.....$mA$.

In a transformer,the number of turns in the primary coil is $140$ and that in the secondary coil is $280$. If the current in the primary coil is $4\,A$,then the current in the secondary coil is.....$A$.

For the given logic circuit,find the output $Y$ in terms of inputs $A$ and $B$.

From which plant are flax fibers obtained?

Which bond angle $\theta$ gives maximum dipole moment for a triatomic molecule $XY_2$?