What are the units of resistance?

Draw a circuit diagram of an electric circuit containing a cell,a key,an ammeter,a resistor of $2\,\Omega$ in series with a combination of two resistors ($4\,\Omega$ each) in parallel and a voltmeter across the parallel combination. Will the potential difference across the $2\,\Omega$ resistor be the same as that across the parallel combination of $4\,\Omega$ resistors? Give reason.

$(a)$ Name the effect of electric current which is utilised in the working of an electrical fuse.
$(b)$ How is a fuse connected in a domestic circuit?

$A$ piece of wire having resistance $R$ is cut into four equal parts. $(a)$ How will the resistance of each part compare with the original resistance? $(b)$ If the four parts are placed in parallel,how will the joint resistance compare with the resistance of the original wire?

Resistivity of two elements $A$ and $B$ are $1.62 \times 10^{-8} \, \Omega m$ and $520 \times 10^{-8} \, \Omega m$ respectively. Out of these two,name the element that can be used to make
$(i)$ filament of electric bulb.
$(ii)$ wires for electrical transmission lines. Justify your answer in each case.

What is the maximum resistance which can be made using five resistors each of $1/5 \ \Omega$ (in $Omega$)?