Answers and Explanations

1. (C) Because carbon has 4 electrons in its outer energy level, it usually forms four covalent bonds to fill each of four sp³ orbitals.

2. (D) Bituminous coal has too much gaseous impurities to burn at a high temperature needed to refine iron ore. It is heated in coke ovens to form the hotter and cleaner burning coke.

3. (C) The reaction of an acid and a carbonate is the usual way to prepare CO₂.

4. (D) The reaction is: CO₂ + Ca(OH)₂ → CaCO₃↓ + H₂O.

5. (B) The lead in a lead pencil is a mixture of graphite and clay.

6. (B) The first alkane is methane, CH₄.

7. (D) The slight oxidation of a primary alcohol produced an aldehyde.

   An example is:

   

8. (E) The functional group for an ester is shown as –COO–.

9. (A) Ethanol can be oxidized into the organic acid enthanoic acid, which has the common name of acetic acid.

10. (C) The formation of an ester is from the reaction of an organic acid and an alcohol. The general equation is:

    

11. (B) Isomers are compounds that have the same composition but differ in their structural formulas.

12. (D) Ethene is the first member of the alkene series that has one double bond. Because it has a double bond, it is said to be unsaturated. The alkane series, which has all single bonds between the carbon atoms in the chain, is called a saturated series.

13. (E) The NH₂⁻ group, called an amine group, makes this structure ethylamine. This type of organic structure is called an amide.

14. (C) The methyl (CH₃–) group and the propyl (–C₃H₇) group attached to a center oxygen (–O–) makes this methyl propyl ether (methoxypropane).

15. (A) Propane is the third member of the alkane series, which is made up of a chain of single-bonded carbons and hydrogens with the general formula of C_nH_2n+2.

16. (B) Ethanoic acid is composed of a methyl group attached to the carboxyl group (–COOH). The latter is the functional group for an organic acid.

17. (D) The propan- part of the name tells you its basic structure is from propane, which is a three-carbon alkane. The –one part tells you it is a ketone that has a double-bonded oxygen attached to the second carbon in the chain.

18. (B) The ethanoic acid contains the carboxyl group (–COOH) that is shown in (B). This is the identifying functional group for organic acids.

19. (D) The functional group for ketones is a carbon in the chain double bonded to an oxygen atom (). The number in the front tells you which carbon has the double-bonded oxygen attached to it.

20. (E) The amine group is the nitrogen with two hydrogens, (–NH₂), attached to a chain carbon. These are basic to the amino acid structures in the body.