Which are physical changes? Select all that apply.
cleaning stains with bleach
curling hair with rollers
cutting cheese with knife
cooking egg whites in skillet

An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons

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.)

Calculate the concentration of all species in a 0.165 m solution of h2co3.