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1.</h3>
C) The volume of the gas is proportional to the number of moles of gas particles.
The Avogadro's law applies to ideal gases with constant pressure and temperature. By that law, the volume of an ideal gas is proportional to the number of moles of particles in that gas.
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B) The gas now occupies less volume, and the piston will move downward.
Boyle's Law applies to ideal gases with a constant temperature. The volume of an ideal gas is inversely related to its pressure. A high pressure drives gas particles together, such that they occupy less volume. The gas trapped inside the piston has a smaller volume. As a result, the the piston will move downward.
Alternatively, consider the forces acting on the piston. Both the atmosphere and gravity are dragging the piston down. In order for it to stay in place, the gas below it must exert a pressure to balance the two forces. Now the pressure from outside has increased. The gas inside needs to increase its pressure. It needs a smaller volume to create that extra pressure. As a result, its volume will decrease, and the piston will move downwards.
Alpha decay involves the loss of an alpha particle, aka a helium nucleus. This results in the mass number of the original element decreasing by 4 and the atomic number decreasing by 2. Assuming 23942u is uranium (92), the resulting element's atomic number is 90, making it thorium.
4.88x10^20 H2O2 molecules
First, you need to find the mass of 1 mol of sugar. Mass, or molar mass, can simply be found by adding the masses of the individual elements. These are given to you on the periodic table.

12 x 12.011 grams (molar mass of Carbon) = 144.132 g
22 x 1.008 grams (molar mass of Hydrogen) = 22.176 g
11 x 15.999 grams (molar mass of Oxygen) = 175.989 g
Add all of the pieces together.
144.132 g + 22.176 g + 175.989 g = 342.297 grams
So, if one mole has 342.297 grams, then 7.35 of that amount will be your answer.
342.297 g/mol x 7.35 mol = 2,515.88 grams