I hope u guys can help me to solve question no ii and iii which is dc voltmeter loading effect. Thank you in advance

 

when you put the voltmeter across the resistor,its own internal resistance has an effect on the reading, the meter is acting as a resistor in parallel and lowers the Actual voltage, so you need to use a voltmeter with the highest internal resistance to get a more accurate reading.

the actual Voltage across each resistor is 12V, so if you calculate the"effective " resistance with meter, then you use ohms law to give the volmeter readings.