If ${N_a} = \{ an : n \in N \}$,then ${N_3} \cap {N_4} = $

Milk is an example of

$A$ flask of volume $10^3 \text{ cc}$ is completely filled with mercury at $0 \ ^\circ\text{C}$. The coefficient of cubical expansion of mercury is $180 \times 10^{-6} / ^\circ\text{C}$ and that of glass is $40 \times 10^{-6} / ^\circ\text{C}$. If the flask is now placed in boiling water at $100 \ ^\circ\text{C}$,how much mercury (in $\text{cc}$) will overflow?

Two resistances $X$ and $Y$ are connected in the two gaps of a meter bridge,and the null point is obtained at $20 \text{ cm}$ from the zero end. When a resistance of $20 \text{ } \Omega$ is connected in series with the smaller of the two resistances $X$ and $Y$,the null point shifts to $40 \text{ cm}$ from the left end. The value of the smaller resistance in ohms is:

$A$ small sphere carrying a charge $q$ is suspended by a string of length $L$ between two parallel plates. The time period of the pendulum is $T_0$. When the capacitor is charged,the time period changes to $T$. The ratio $T/T_0$ is equal to:

The figure shows a plot of binding energy per nucleon $E_b$ against the nuclear mass $M$. $A, B, C, D, E, F$ correspond to different nuclei. Consider four reactions:
$(i)$ $A + B \to C + \varepsilon$
$(ii)$ $C \to A + B + \varepsilon$
$(iii)$ $D + E \to F + \varepsilon$
$(iv)$ $F \to D + E + \varepsilon$
where $\varepsilon$ is the energy released. In which reactions is $\varepsilon$ positive?