(3) HF because HCl is an acid and it seperates easily into water. Flourine has the highest electronegativity so im guessing because it pulls the electrons the hardest that it has the strongest bonds.
Properties of metals:
High melting points
High density
Ductile
Malleable
Good conductors of electricity
Good conductors of heat
I think if you added a proton you would have chlorine.
The noble gasses are the he chemical elements in group 18 of the periodic table. The gasses in this family include helium, neon, argon, krypton, xenon, and radon. All these gasses are colorless are oderless, elements in this family have atoms with a full outer shell of electrons. They are also called inert gasses.
Six valence electrons
Answer:- 448 mL of hydrogen gas are formed.
Solution:- It asks to calculate the volume of hydrogen gas formed in milliliters at STP when 0.020 moles of magnesium reacts with excess HCl acid. The balanced equation is:

There is 1:1 mol ratio between Mg and hydrogen gas. So, the moles of hydrogen gas is also equals to the moles of Mg reacted.
moles of Hydrogen gas formed = 0.020 mol
At STP, volume of 1 mol of the gas is 22.4 L. We need to calculate the volume of 0.02 moles of hydrogen gas.

= 0.448 L
They want answer in mL. So, let's convert L to mL using the conversion formula, 1L = 1000mL

= 448 mL
So, 0.020 moles of magnesium would produce 448 mL of hydrogen gas at STP on reacting with excess of HCl acid.
Answer:
Hydrocarbon is a Compound that is made up of Carbon and Hydrogen .