What will happen to the current in a circuit,if its resistance is doubled?

If five equal pieces of wire having $5\, \Omega$ resistance are made and connected in parallel,then their equivalent resistance will be $......$

When do we say that the resistors are connected in series?

Which alloy is used to make the heating element (resistance wire) in an electric iron?

What are the factors on which the resistance of a conductor depends?

$A$ cylinder of a material is $10\, cm$ long and has a cross-section of $2\, cm^{2}$. If its resistance along the length is $20\, \Omega$,what will be its resistivity in number and units?