Answer:NaF is ionic. NF3 is covalent. SiF4 is ionic. CaF2 is Ionic and NH4F is also ionic. Ionic compounds transfer electrons whereas covalent compounds share electrons hence the word "co". Also, ionic compounds are formed with metal and nonmetal. Where a covalent is with 2 nonmetals. Only ionic compounds would produce fluoride in water because ionic compounds can dissolve in water and covalent compounds cant.
Answer:

Explanation:
Step 1. Identify the Group that contains X
We look at the consecutive ionization energies and hunt for a big jump between them

We see a big jump between n = 2 and n = 3. This indicates that X has two valence electrons.
We can easily remove two electrons, but the third electron requires much more energy. That electron must be in the stable, filled, inner core.
So, X is in Group 2 and P is in Group 15.
Step 2. Identify the Compound
X can lose two valence electrons to reach a stable octet, and P can do the same by gaining three electrons.
We must have 3 X atoms for every 2 P atoms.
The formula of the compound is
.
Answer:
all of these are properties of metalloids
D. It is the heat required to change a gram of substance from a liquid to a gas.
Explanation:
The heat of vaporization is the heat required to change a gram of substance from a liquid to a gas.
- It is also known as the enthalpy of vaporization.
- The heat of vaporization is the quantity of heat needed to change one gram of a substance from liquid to gas.
- This heat of vaporization is dependent on the pressure conditions the process is taking place.
- Different liquids have their heat of vaporization.
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Answer:
combination of a very light gas (hydrogen) and a substance that is found in all living things (carbon). Hydrocarbons are found in petrol, coal and natural gas