Nacl is soluble in water and …

Just remember that like dissolves like. The same way, polar dissolves polar compounds. In this case, NaCl is polar so it gets dissolved in water(which we know is also polar). On the other hand, petroleum is a non polar compound, Therefore, NaCl does not dissolve in it. 

Sodium chloride is an ionic molecule. There exists electronegativity difference between Sodium and Chlorine, which gives polarity to the molecule. Thus sodium chloride is polar molecule.

Generally polar molecules will soluble in polar solvents and insoluble in non-polar solvents. Non-polar molecules will soluble in non-polar solvents and insoluble in polar solvents.

As sodium chloride is polar molecule it will be soluble in polar solvents like water. And insoluble in petrol (as it is non-polar solvent).