The resistance of 100 ohm and 200 ohm are connected in series with the 220V main.When a volt meter of 1000 ohm resistance is connecte in parallel to 100 ohm then the reading of voltmeter is?

Dear student, 

Parallel of 100 ohm and 1000 ohm, 
$R=\frac{1000\times 100}{1000+100}=\frac{1000}{11} \mathrm{ohm}$
Effective resistance of circuit, 
 $R_{eff}=\frac{1000}{11}+200 =290.90 \mathrm{ohm}$
Total current drawn from battery, 

$\frac{V}{R_{eff}}=\frac{220}{290.90}=0.687 \mathrm{A}$

 Now, reading of voltmeter = total voltage - voltage drop across 200 ohm 
$$\begin{gathered} V_{reading}=220-\left(I\times 200\right) \\ \Rightarrow V_{reading}=220-\left(0.687\times 200\right)=82.5 \mathrm{V} \end{gathered}$$

Regards.