Ôn Tập Môn Hóa Lớp 7

How many compounds are there among the given substances: water (H2O), table salt (NaCl), oxygen gas (O2), nitrogen gas (N2), limestone (CaCO3)?

• 1

• 2

• 3

• 4

What is the molecular weight of carbon dioxide (CO2)?

• 28 amu

• 44 amu

• 32 amu

• 16 amu

Under normal conditions, noble gases exist as stable monatomic forms, difficult to undergo chemical changes. The outermost electron layer of them (except He) contains how many electrons?

• 4 electrons

• 6 electrons

• 8 electrons

• 10 electrons

Which of the following substances is formed by covalent bonding?

• NaCl

• CO2

• MgO

• FeO

Ionic bonds are formed due to what?

• The attraction between oppositely charged ions.

• The attraction between ions with the same positive charge.

• The attraction between ions with the same negative charge.

• The attraction between neutral atoms.

When forming a bond in magnesium oxide (MgO), how many electrons did the Mg atom donate from its outermost layer to the O atom to form an ion with a stable shell like the noble gas Ne?

• 1

• 2

• 3

• 4

The methane molecule consists of one carbon atom bonded to four hydrogen atoms. When forming covalent bonds in methane, how many electrons does the carbon atom share with each hydrogen atom?

• The carbon atom shares 1 electron with each hydrogen atom.

• The carbon atom shares 2 electrons with each hydrogen atom.

• The carbon atom shares 3 electrons with each hydrogen atom.

• The carbon atom shares 4 electrons with each hydrogen atom.

The bond between atoms in a water molecule is what type of bond?

• covalent

• ionic

• metallic

• non-metallic

The chemical bond between oxygen and hydrogen atoms in a water molecule is formed by what?

• Oxygen atom receives electrons, hydrogen atom donates electrons.

• Oxygen atom donates electrons, hydrogen atom receives electrons.

• Oxygen atom and hydrogen atom share electrons.

• Oxygen atom...

In the oxygen molecule (O2), when two oxygen atoms bond with each other, they

• share protons.

• transfer electrons from one atom to another.

• transfer protons from one atom to another.

• share electrons.