In which type of connection of resistors will the equivalent resistance increase?

Resistance $n$,each of $r \ \Omega$,when connected in parallel give an equivalent resistance of $R \ \Omega$. If these resistances were connected in series,the combination would have a resistance in $\Omega$,equal to

The resistance of the series combination of two identical resistors is $S$. When they are joined in parallel,the total resistance is $P$. If $S = nP$,then the minimum possible value of $n$ is

Three conductors draw currents of $1 \,A, 2 \,A$ and $3 \,A$ respectively, when connected in turn across a battery. If they are connected in series and the combination is connected across the same battery, the current drawn will be

$A$ Copper $(Cu)$ rod of length $25 \, cm$ and cross-sectional area $3 \, mm^2$ is joined with a similar Aluminium $(Al)$ rod as shown in the figure. Find the resistance of the combination between the ends $A$ and $B$ (in $m\Omega$).
(Take Resistivity of Copper $= 1.7 \times 10^{-8} \, \Omega \cdot m$,Resistivity of Aluminium $= 2.6 \times 10^{-8} \, \Omega \cdot m$)

The resistance across $M$ and $N$ in the given figure is