Que signo de puntuación se usa para separar fechas de un periodo de tiempo

Which ion was formed by providing the second onization energy to remove an electron?

Answer these simple questions for me. number them also do it will be easy for me. don’t put random words.

Okay so i'm taking an online spanish course (penn foster), and in the study guide, you have to create a bunch of sentences with words you've learned so far. translating, reading, and those kinds of things are fairly easy, but when it comes to making my own sentences, my brain just kinda waltz's away. anyone got any tips?