What are the answers to questions 18-21 concerning solubility, Raoult's law, ionization energies, and complex compound nomenclature?

voici les réponses aux questions :

18. The sulphates of Ca, Sr are insoluble in water because

• B) their lattice energy is higher than their hydration energy.

19. Raoult's law states that

• B) The partial vapour pressure of each component in a solution is directly proportional to its mole fraction in the solution.

20. Why is it that elements in group I of the periodic table have low ionization energies?

• A) It is easy to remove an electron from their outermost shell.

21. The correct name for the complex compound $\text{K}_3[\text{Co}(\text{NO}_2)_6]$ is:

• C) Tripotassium hexanitrocobaltate(III)