Transformer - I connected 50k resistance which burnt - why? AC
It's hard to understand exactly what you are asking, but I will go for the question in the title of the question.

The power dissipated in a resistor is
$$P_R = V_R^2/R$$
where \$V_R\$ is the voltage across the resistor and \$R\$ is the resistor value. So, if you put \$47\mathrm{k}\Omega\$ directly across 230 V the resistor will dissipate 1.13 W. That's a lot for a common resistor, which is probably rated for 0.125 W or 0.25 W. It's no surprise that the resistor would burn up. On the other hand, if you do the same thing with a \$2\mathrm{M}\Omega\$ resistor the power dissipated is only 26 mW...it probably won't even get warm.