6) Calculate the density of sulfuric acid if 35.4 mL of the acid weighs 65.14 g. 7) Find the mass of 250.0 mL of benzene. The density of benzene is 0.8765 g/ml. 8)

Density= mass/volume so 5.1 divided by 4.7 is  5.1 / 4.7 =1.08510638298round to the correct number of sig figs

The answer is solid copper 

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.