The correct description for an atom of helium would be option C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.
According to Boyle's Law, P1V1 = P2V2
where P1 and V1 are initial pressure and volume respectively. P2 and V2 are final pressure and volume receptively.
Given: P2 = 4 P1 and V1 = 10.0l
∴ V2 = 2.5 l
Answer: Final volume of system is 2.5 l
The chemical reaction of Cavendish involving zinc would be a reaction between hydrochloric acid and zinc yielding zinc chloride and hydrogen gas. The balanced chemical equation would be:
2Zn + 2HCl = 2ZnCl + H2
This is an example of a single replacement reaction where zinc replaces hydrogen in the acid molecule.
The answer is 3). This is because elements are the simplest form of a substance, and cannot be broken down any further. Compounds on the other hand are much more complex than elements and can be broken down INTO elements.
For example, Na, sodium, is an element and cannot be broken down further. H2O, water, is a compound and can be broken down into Hydrogen and Oxygen.
