Grade 7 Unit 1

|. Nitrate and nitrite groups are different in the ------------

• a.type of atoms

• . b. number of atoms.

• c. valency.

• d. type of charge.

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

• a. monovalent.

• b. divalent.

• c. trivalent.

• d. tetravalent.

. All of these salts dissolve in water, except...........................

• a. sodium chloride.

• b. potassium sulphate.

• c. silver chloride.

• d. sodium sulphide.

A lithium atom (Li) changes into a lithium ion (Li*), which means that it ---.-.-.-.--

• a. gains one proton.

• b. gains one electron.

• c. loses one proton.

• d. loses one electron.

All the following are properties of inert gases, EXCEPT.................................

• a. they don’t participate in chemical reactions.

• b. their outermost electron shells are completely filled.

• c. they form negative ions.

• d. their molecules consist of one single atom.

The bond in a sodium chloride molecule is ---- bond.

—

• a. single covalent

• b. double covalent

• c. triple covalent

• d. ionic

The covalent bond usually arises between ---.-------- elements.

• a. two metallic

• b. two nonmetallic

• ¢. metallic and nonmetallic

• d. metallic and noble

Increasing the ratio Of............. gas in the atmosphere leads to increasing the temperature.

_

• a. carbon monoxide

• b. carbon dioxide

• c. nitric oxide

• d. sulphur dioxide