What is the atomic mass of gallium which occurs as 60% gallium and 40% gallium-71? Need to show work

Achemist determined by measurements that 0.0300 most of beryllium oxide participate in a chemical reaction calculate the mass of berlylium oxide that participates

What is the percentage by mass of silicon (si) in iron aluminum silicate (fe3al2(sio4)3)?

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.)