7. Atomic mass
8. Atomic number
9. Chemical symbol
10. Right
Answer:
a. because it is an element
Explanation:
its pure because it only has one type of atom, making it an element
Answer: 8 electrons
Explanation: Valence electrons are the electrons in the outermost shell of an atom and they are important in chemical reactions.
Atoms are <em>happy</em> when they follow the octet rule which states that 2 electrons can go in the first shell and 8 electrons can go in the other shells.
Electrons are happy when they have a full outer shell which usually needs to be 8 electrons. However, some of the smaller elements like helium are happy because they can hold a max of 2 electrons and helium has 2 electrons since it has 2 protons in its core as well as 2 electrons in its energy levels.
Answer:
Inhalation (via the respiratory tract)Absorption (via mucous membranes such as the eyes) Ingestion (via the gastrointestinal tract)
Explanation:
The opening where an infectious disease enters the host's body such as mucus membranes, open wounds, or tubes inserted in body cavities like urinary catheters or feeding tubes.
Answer:
The result is 3.859 in which we use four significant figures.
Explanation:
We start by solving the mathematical operation :

The result for the operation is 3.859438 but the numbers in the operation are given with four significant figures and that is why we are going to use four significant figures to express the result
To express 3.859438 with four significant figures we use the first four digits that appear from left to right starting by the first digit that is different to zero
In this case : 3.859 will be the result with four significant figures.
We also use a rule that says : To decide if the last significant figure remains the same we look for the value of the digit at its right.
If that number is greater than or equal to 5 ⇒ we sum one to the last significant figure
For example 3.859738 = 3.860 with four significant figures because the ''7'' is greater that 5
If that number is less than 5 ⇒ the last significant figure remains the same
In our case : 3.859438 = 3.859 because ''4'' is less than ''5''