Which element, represented by x, reacts with fluorine to produce the compound xf2?
(1) aluminum (3) magnesium
(2) argon (4) sodium

The answer is (3) magnesium. Aluminum usually has valence of +3 and Sodium usually has valence of +1. Argon is usually not react with others. Because it is already stable with 8 electrons at the outer shell.

Read the sentences below in 1962, i tried to enroll as the first black student at the university of mississippi. the governor of mississippi blocked my entrance which best describes the verbs used in the sentences? o they are past tense verbs, which are often used in narrative essays o they are past tense verbs, which are not often used in narrative essays. o they are future tense verbs, which are often used in narrative essays o they are future tense verbs, which are not often used in narrative essays.

While unproven, it uses facts to support part of a conclusion. it is still factual and has predictive power, however.