Can you please help me What are the steps of preparing a 3m solution of NaOH?

(Its talking about molality)

Predict the products butane (c4h10) + oxygen —>

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

Achemical reaction is done in the setup shown, resulting in a change of mass. what will happen if the same reaction is done in a sealed container that is placed on the electronic balance?