How much pressure would 4.85 moles of He gas exert in a 4.50 L tank at 55° C?

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?

The sum of the oxidation numbers in a neutral compound is always