What do atoms when they share electron pairs

Ab c or d ? i’m not sure what the answer is

Ablock of aluminum is dropped into a graduated cylinder with an initial volume of water at 75ml and the volumes rises to 90ml. if the block has a mass of 40.5 g what is its density ?

If you need to add 27.50ml of a solution, which piece of glassware would you use to deliver this volume and explain how you would determine if the 27.50 ml was measured?