What statements correctly describe the crystal structure of halite?

The unit cell consists of eight ions: four are Na+ ions and the other four are Cl– ions.
The crystal structure is face-centered cubic (FCC).
The sodium ions occupy the lattice points.
The crystal structure is body-centred cubic (BCC).
Each ion in this lattice has six of the other kind of ion as its nearest neighbors.

Lab reagent, hypothesis test.a reference solution used as a lab reagent is purported to have a concentration of 5 mg/dl. six samples are taken from this solution and the following concentrations are recorded: (5.32, 4.88, 5.10, 4.73, 5.15, 4.75) mg/dl.these six measurements are assumed to be an srs of all possible measurements from solution.they are also assumed to have a standard deviation of 0.2, a normal distributin, and a mean concentration equal to the true concentration of the solution.carry out a significance test to determine whether these six measurements provide reliable evidence that the true concentration of the solution is actually not 5 mg/dl.