HELP PLEASE 140 grams of lead (II) nitrate are dissolved in water then mixed with a solution containing 75 grams of sodium chloride. The reaction creates the precipitate, lead (II) Chloride, and a solution of sodium nitrate. How many grams of lead (II) Chloride can be produced given the initial amount of lead (II) nitrate?

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

Compare and contrast physical changes with chemical changes.

Aglow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion.