17. La disposición de Mendeléiev colocaba los
?
a)elementos con propiedades similares en columnas verticales o grupos.

b)elementos con propiedades similares en columnas horizontales.

c)elementos con propiedades similares en filas horizontales o periodos.

d)elementos con propiedades similares en filas verticales.

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.

Iam pretty sure that the answer is d