Answer:

Explanation:
<u>1. Convert Atoms to Moles</u>
We must use Avogadro's Number: 6.022*10²³. This is the number of particles (atoms, molecules, ions, etc.) in 1 mole of a substance. In this case, the particles are atoms of helium. We can create a ratio.

Multiply by the given number of helium atoms.

Flip the fraction so the atoms of helium cancel.



<u>2. Convert Moles to Grams</u>
We must use the molar mass, which is found on the Periodic Table.
Use this as a ratio.

Multiply by the number of moles we calculated. The moles will then cancel.



<u>3. Round </u>
The original measurement has 3 significant figures (5, 5, and 0). Our answer must have the same. For the number we calculated, it is thousandth place. The 3 in the ten thousandth place tells us to leave the 5.

The mass is <u>0.365 grams of helium</u> so choice A is correct.
JJ Thomson discovered electrons using the cathode ray. Electrons are negatively charged particles that orbit around the nucleus of an atom. Finding out that there was a negative charge to balance out the positive charge. This later helped develop Hund's Rule and the Pauli Exclusion Principle.
Answer: D is right
Explanation: One mole contains 6.0225 ·10^23 molecules
Despite of the substance
Answer:
the melting process begins right away because the air temperature around the ice cubes is warmer than the temperature in the freezer
All scientists try to base their conclusions on data and measurements.