What elements are nonmetals but aren't halogens or noble gasses?

Which of these properties, used alone, would be least useful in identifying most minerals? a. color b. luster c. streak d. density

Define dew point. i am writing this part to be able to ask the question

Sodium sulfate dissolves as follows: na2so4(s) → 2na+(aq) + so42- (aq). how many moles of na2so4 are required to make 1.0 l of solution in which the na concentration is 0.10 m?