Fluorine is the most active chemical element, reacting with virtually every element. It even reacts with the noble gases at high temperatures and pressures. The noble gases, or Group 18 (VIIIA), also known as the inert gases, generally do not react with other elements.
Explanation:
Question:
A student weighed an empty graduated cylinder. It weighed 35.86 g. She then carefully added water to the graduated cylinder until it reached the 7.5 mL mark. When she weighed the graduated cylinder again, this time with the 7.5 mL of water in it, it weighed 43.18 g. What was this student's experimental density of water?
Answer:
0.976 g/mL
Explanation:
Weight of empty cylinder = 35.86g
Volume of water = 7.5mL
Weight of cylinder + water = 43.18g
Experimental density = ?
Density of water = Mass of water / volume of water
Mass of water = (Weight of cylinder + water) - Weight of empty cylinder
Mass of water = 43.18 - 35.86 = 7.32g
Density = 7.32 / 7.5 = 0.976 g/mL
Ni (Nickel) is the best conductor, and in fact the only conductor, in that list
Hydrogen bonds are present in the following molecules: HF AND NH3
Dipole dipole inter molecular forces occurs the molecules of H2S AND H2.
Hydrogen bonding is an electrostatic attraction between two polar groups that occur when hydrogen atom covalently bound with highly electronegative atoms.
Answer: The correct option is 3.
Explanation: We are given a compound which is made up of iron and oxygen only. The ratio of the two are given as:

This means that, number of iron ions are 2
Number of oxide ions are 3
From the above information, the formula becomes : 
The valency of iron = 3
Valency of oxide = 2
This compound is named as iron (III) oxide.
Hence, the correct option is 3