Question

1. the structures of two allotropes of carbon are represented above. which of the following statements best helps explain why diamond is much harder than graphite? a. diamond contains covalent bonds, whereas graphite contains ionic bonds. b. diamond contains ionic bonds, whereas graphite contains covalent bonds. c. carbon atoms in diamond have four covalent bonds, whereas graphite is made of layers that are held together by relatively weak dispersion forces. d. carbon atoms in diamond have a sea of mobile electrons that make the structure strong, whereas graphite does not contain delocalized electrons. 7. a gaseous air - fuel mixture in a sealed car engine cylinder has an initial volume of 600. ml at 1.0 atm. to prepare for ignition of the fuel, a piston moves within the cylinder, reducing the volume of the air - fuel mixture to 50.ml at constant temperature. assuming ideal behavior, what is the new pressure of the air - fuel mixture? a. about 0.083 atm, because the initial volume of the gas mixture was 12 times larger than its final volume. b. about 12 atm, because the volume of the gas mixture decreased by a factor of 12. c. about 120. atm, because the initial volume of the gas mixture was 120 times larger than its final volume. d. about 550. atm, because the change in the volume of the gas mixture was 550 ml

Explanation:

6.

Diamond has a three - dimensional network of covalent bonds with each carbon atom having four covalent bonds. Graphite has layers held together by weak dispersion forces. Strong covalent bonds in diamond make it hard. Options A and B misidentify bond types. Option D is incorrect about delocalized electrons in graphite.

Step1: Identify the gas law

Since temperature is constant, we use Boyle's law $P_1V_1 = P_2V_2$.

Step2: Rearrange for $P_2$

$P_2=\frac{P_1V_1}{V_2}$.

Step3: Substitute values

$P_1 = 1.0$ atm, $V_1=600$ mL, $V_2 = 50$ mL. So $P_2=\frac{1.0\ atm\times600\ mL}{50\ mL}= 12$ atm.

Answer:

C. Carbon atoms in diamond have four covalent bonds, whereas graphite is made of layers that are held together by relatively weak dispersion forces.

7.