How is a voltmeter connected in a circuit?

$A$ metal has a very large number of free electrons and a non-metal has a very small number of free electrons.

Which of the following represents voltage?

You are given three resistors of $10\, \Omega, 10\, \Omega, 20\, \Omega$,a battery of emf $2.5\, V$,a key,an ammeter,and a voltmeter. Draw a circuit diagram showing the correct connections of the given components such that the voltmeter gives a reading of $2.0\, V$.

How many joules are there in one kilowatt-hour?

State the factors on which the heat produced in a current-carrying conductor depends. Give one practical application of this effect.