What is the equivalent resistance of the circuit in $\Omega$?

In the given circuit, what is the reading of the voltmeter in $V$?

Find the equivalent resistance between points $A$ and $B$ in the network of resistors,each of resistance $r \Omega$.

The resistance of a voltameter is $2\,\Omega$. It is connected in series to a battery of $10\,V$ through a resistance of $3\,\Omega$. In a certain time,the mass deposited on the cathode is $1\,g$. Now,the voltameter and the $3\,\Omega$ resistance are connected in parallel with the battery. The increase in the deposited mass on the cathode in the same time will be .............. $g$.

$A$ voltmeter of resistance $998\ \Omega$ is connected to a cell of $emf$ $2\ V$ and internal resistance $2\ \Omega$. The error in the measurement of $emf$ will be:

$A$ circuit is comprised of eight identical batteries and a resistor $R = 0.8\,\Omega$. Each battery has an $emf$ of $1.0\, V$ and internal resistance of $0.2\,\Omega$. The voltage difference across any of the batteries is ............. $V$.