Answer : The concentration of luminol in the solution is, 1.20 M.
Explanation : Given,
Mass of luminol = 16.0 g
Volume of solution = 75.0 mL
Molar mass of luminol = 177.16 g/mole
Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.
Formula used :

Now put all the given values in this formula, we get:

Therefore, the concentration of luminol in the solution is, 1.20 M.
Answer: The solid turns into liquid during melting.
Explanation:
a. The process of a solid turning into liquid is called melting. The solid ice turns into a liquid during the melting process. The solid molecules gain energy and flow as a liquid.
b. The energy of the molecules increases in the liquid state. When the ice turns into a liquid the energy of the molecules increases. The application of heat or excess temperature increases the energy of the molecules.
Physical. chemical only applies when it undergoes a reaction
The answer is 4.69 x 10⁻¹⁹ I hope this helped!