Think of it this way: it is a distribution problem in which you are multiplying the 2 on the outside with each element in the parentheses. Oxygen does not have a number in front of it, so put an imaginary one in front of it to help you. Do the same with Hydrogen since it doesn't have a number in front of it either. Now you know that hydrogen has one ion and oxygen has one... but you must now multiply each of the elements' ions by two. You should now know that Oxygen has 2 ions in Calcium Hydroxide and that there are also 2 ions of Hydrogen in Calcium Hydroxide. Does this make sense?
Because the there’s not enough inertia to keep the bouncy ball going at the same rate
The level in the beaker will increase because the volumes of the spheres will also be added to the volume of the water. First, we must determine the volume of each sphere. For this, we will use:
density = mass / volume
We can check the density of both aluminum and iron in literature, and given the mass, we may obtain the volume.
Aluminum:
Density = 2.70 g/ml
Mass = 20.4 g
Volume = 20.4 / 2.7 = 7.56 ml
Iron:
Density = 7.87 g/ml
Mass = 49.4 g
Volume = 49.4 / 7.87 = 6.28 ml
Now, we add these volumes to the volume of water present:
75.2 + 6.28 + 7.56 = 89.04
The new level will be 89.0 ml