Final answer:
The new volume of the burette after adding 20 drops of water can be calculated by adding the volume of the drops to the initial volume.
Step-by-step explanation:
The volume of water in the burette is initially 35 cm³. We are then adding 20 drops of water, each with a volume of 0.15 cm³. To find the new volume, we can add the volume of the drops to the initial volume:
New volume = initial volume + volume of drops
New volume = 35 cm³ + (20 drops * 0.15 cm³/drop)
New volume = 35 cm³ + 3 cm³
New volume = 38 cm³
Therefore, the new volume is 38 cm³, which corresponds to option a).