When three resistors of $5 \Omega$,$10 \Omega$,and $30 \Omega$ are connected in parallel in a circuit,what will be the equivalent resistance?

Why are alloys used to make standard resistors?

If three resistors of $5 \Omega$,$10 \Omega$,and $15 \Omega$ are connected in series,the equivalent resistance $R$ is equal to ........ (in $Omega$)

Mention one reason why tungsten is used for making the filament of an electric lamp.

If three bulbs of $100 \; W$, $60 \; W$, and $40 \; W$ are used for $2 \; \text{hours}$ daily in a house, how many units of electrical energy are consumed in $30 \; \text{days}$?

Draw a circuit diagram for a circuit consisting of a battery of five cells of $2 \text{ V}$ each, a $5 \, \Omega$ resistor, a $10 \, \Omega$ resistor, and a $15 \, \Omega$ resistor, an ammeter, and a plug key; all connected in series. Also, connect a voltmeter to record the potential difference across the $15 \, \Omega$ resistor and calculate:
$(i)$ the electric current passing through the above circuit and
$(ii)$ the potential difference across the $5 \, \Omega$ resistor when the key is closed.