How many moles of oxygen (o2) are required to completely react with 27.4 mol of h2?

Particle model to predict what will happen if a sharp object creates a hole in the soccer ball

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.)

The volume of an unknown substance in a sealed glass jar is 50 milliliters. the volume of the jar is 200 milliliters. which state of matter could the substance be?