(1) According to the experimental process, the mass fraction of sodium chloride in the sample was calculated by measuring the mass of silver chloride.

So the answer is: the quality of silver chloride;

(2) According to the experimental process, the mass fraction of sodium chloride in the sample can be calculated by the mass of silver chloride generated by precipitation, so silver nitrate and nitric acid should be added to the solution to convert chloride ions into silver chloride precipitation; Operation I is to separate the precipitate from the solution, and filtration operation should be taken.

So, the answer is: agno 3；; Filtering;

(3) Sodium nitrate, sodium glutamate and other substances will adhere to the surface of silver chloride and precipitate. If it is not washed, the mass of precipitated silver chloride will be too large, and the mass of sodium chloride in the calculated sample will also be too large.

So the answer is: wash away the impurities attached to the surface of sodium chloride; Too big;

(4) The amount of silver chloride = 5.74g143.5g/mol = 0.04mol, and according to the conservation of chloride ion, n(NaCl)=0.04mol, then the mass fraction of sodium chloride in the sample = 0.04mol× 58.5g/mol10g×/kloc-0.

So the answer is: 23.4%; Unqualified;

(5) The concentration of sodium chloride in the solution is 0.04mol0. 1L=0.4mol/L,

So the answer is: 0.4.