[CHEMISTRY GRADE 10] - CHEMICAL BONDING.

The correct formula for a copper atom that has lost two electrons is

• Co⁺ .

• Co2+ .

• Cu²⁻ .

• Cu²⁺ .

Which of the following is not a characteristic of a salt?

• hardness.

• a high melting point.

• an ability to conduct electric current in the molten state.

• an ability to conduct electric current in the solid state.

The correct formula for ammonium phosphate is

• (NH₄)₃PO₄

• (NH₄)₂PO₄.

• NH₄PO₄.

• NH₄(PO₄)₂.

Element X and Y react to form compound Z. Element X loses 1 electron and element Y gains 2 electrons. A student writes three statements about the reaction:

(1) Z is an ionic compound.

(2) The formula of Z is X₂Y.

(3) The charge on the ion of element Y is 2+.

Which statements are correct?

• (2) and (3).

• (1) and (2).

• (1), (2) and (3).

• (1) and (3).

How many valence electrons are indicated by the following electron configuration?

1s²2s²2p⁶3s²3p⁵

• 2.

• 5.

• 3.

• 7.

Metals tend to lose one or more electrons to form

• cations.

• anions.

• polyatomic ions.

• unit cells.

A polar covalent bond is likely to form between two atoms that

• differ in electronegativity.

• are of similar size.

• differ in state of matter.

• have the same number of electrons..

The Lewis structure of methane, CH₄, has

• two double bonds.

• one triple bond.

• four single bonds.

• two single bonds and two double bonds

The series of substances containing nonpolar covalent bonds is

• Cl₂, O₃, H₂O.

• K₂O, Cl₂, O₃.

• O₂, O₃, H₂O.

• O₃, O₂, H₂.

Which statement about ion and ionic bonds is correct?

• Bromine atoms form negatively charged bromide ions.

• Positive ions are formed when atom lose protons.

• Sodium ions have an equal number of protons and electrons.

• Ionic bonding involves sharing of pairs of electrons.