Which of the following illustrates a single-replacement reaction? A. CaCl2 + Na2CO3 → CaCO3 + 2Naci
O B. 2Fe + 3Br2 → 2FeBr3
O C. Ba(NO3)2 + NISO4 → BaSO4 + Ni(NO3)2
D. Fe + CuSO4 → Cu + FeSO4

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.

Can someone me with 3 and 4 plz. this is for masteries test.

Which is an example of a reversible physical change?