Masses of elements in periodic table are measured relative to

• mass of 1 electron

• mass of 1 hydrogen atom

• mass of 1/12 carbon atom

• mass of 12 carbon atoms

For an atom with no charge, the atomic № is equal to

• № of protons

• № of neutrons

• № of protons and electrons

• № of protons and neutrons

Which of the following chemical elements has 12 neutrons?

• Magnesium (Mg)
• Argon (Ar)

• Carbon (C)

• Calcium (Ca)

Number of electron shells (levels) in the atom is equal to

• atomic №

• group №

• period №

• mass №

Which element is an alkali metal?

• chlorine (Cl)

• potassium (K)

• oxygen (O)

• argon (Ar)

Which of the following elements is NOT a noble gas?

• argon

• neon

• xenon

• silicon

Noble gases are unreactive because

• they are gases

• they have molecules made of one atom

• they have complete outer shell

• they have equal number of protons and neutrons

Which halogen is a solid at room temperature?

• fluorine

• chlorine

• bromine

• iodine

Which of the following elements has the highest value of electronegativity?

• Fluorine (F)

• Nitrogen (N)

• Sodium (Na)

• Francium (Fr)

Choose the correct electron configuration for fluorine, ⁹F?

• [9]

• [7.2]

• [2.7]

• [10.9]