How many times was Obama re-elected as an Illinois state senator? once twice three times four times

Find the number of grams of hcl needed to react completely with .50 moles of magnesium.

100 grams of molten lead (600°c) is used to make musket balls. if the lead shot is allowed to cool to room temperature (21°c), what is the change in entropy (in j/k) of the lead? (for the specific heat of molten and solid lead use 1.29 j/g⋅°c; the latent heat of fusion and the melting point of lead are 2.45 × 104 j/kg and 327°c, respectively.)

What is a number added in front of a formula in order to balance the equation