chemical combinations

When a nonmetal gains or shares by two electrons, its valency will be ….

• tetravalent

• monovalent

• divalent

All of the following elements are divalent except ……

• ₁₂ Mg

• ₇N

• ₈O

• ₁₆S

The valency of ferrous is………

• monovalent

• divalent

• trivalent

In trivalent elements, the outermost energy level contains …… electrons.

• (3) or (5)

• (5) or (6)

• (7) or (1)

The valency of argon (₁₈Ar) is …………

• trivalent

• divalent

• monovalent

• zero

All of the following are monovalent atomic groups except ……… group.

• phosphate

• nitrate

• hydroxide

• bicarbonate

The chemical formula of carbonate group is .........

• (NO₃)^-

• (SO₄)^--

• (NH₃)⁺

• (CO₃)^--

Nitrate and nitrite groups are different in the …….

• type of atoms

• number of atoms

• valency

• type of charge

Each aluminum atom (₁₃AI) combines with .......... atoms of chlorine (₁₇CI) to form aluminum chloride molecule.

• two

• three

• four

• five

The chemical formula of sodium hydroxide is...

• NaHCO₃

• NaCO₃

• NaOH