The functional kidney of a frog tadpole is

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

The $pH$ of a buffer solution decreases by $0.02$ units when $0.12 \ g$ of acetic acid is added to $250 \ mL$ of a buffer solution of acetic acid and potassium acetate at $27^{\circ} C$. The buffer capacity of the solution is

If $A = \begin{bmatrix} 1 \\ 2 \\ 3 \end{bmatrix}$,then $AA' = $

The cork cambium, cork, and secondary cortex are collectively called $........$.

If $A = \{2, 4, 5\}$ and $B = \{7, 8, 9\}$,then $n(A \times B)$ is equal to: