Answer : The mass of NaCl needed would be, 86.1 grams.
Explanation :
Formula used for Elevation in boiling point :

or,

where,
= change in temperature = 
= boiling point constant = 
m = molality
i = Van't Hoff factor = 2 (for NaCl electrolyte)
= mass of solute (NaCl) = ?
= mass of solvent (water) = 1001 g
= molar mass of solute (NaCl) = 58.5 g/mol
Now put all the given values in the above formula, we get:


Therefore, the mass of NaCl needed would be, 86.1 grams.