5. The difference between mass and weight it that mass is the volume inside a object.
Initially, weigh the correct amount of 
calculated from the formula.
Number of moles =
As 1 mole of is given and molar mass of is 
, then
1 mole of = 
Mass of in g = 
Thus,
1 mole of = 58.44 g.
Now, the weighed amount of i.e. 58.44 g is added to a 1 liter container and then add small amount of water in the container to dissolve the salt. After that, fill the container with distilled water to the graduation mark or until the total volume reaches 1 liter.
Thus, option (c) is correct i.e. first put one mole of salt in the container then add the water with stirring till the total volume reaches 1 liter.
there are 1023 atoms in pure aluminium
The mass percentage of Na in NaCl is 39.0%
This means that if there's 100 mg of NaCl , 39 mg of the compound is Na.
For compound to contain 39 mg Na - 100 mg of NaCl should be present.
Therefore for the compound to contain 400 mg - 100/39 x 400 - 1025.6 mg
The mass of NaCl present should be 1.026 g
