Neutral atoms get smaller as you move across the periodic table from (left to right) because the atom increases in electrons. The more electrons, the bigger the effective nuclear charge (electron and proton attraction) and so basically the atom shrinks.
So,
Our conceptual plan is as follows:
g AlCl3 --> mol AlCl3 --> mol H2 --> g H2

Hope this helps!
Answer:
B. To ask and answer scientific questions
The masses of the nucleus and the electron cloud of an atom is balanced if false. Do you have any answer options??