10th grade Why a material's molecules decide what it can do worksheet

Why a material's molecules decide what it can do

Grade 10 Science Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   A polyethylene chain has 1000 repeat units, each C₂H₄ with a mass of 28 g/mol. What is the chain's molar mass, Ari?
2. 2.

   A PTFE chain has 500 repeat units, each C₂F₄ with a mass of 100 g/mol. What is the chain's molar mass, Bo?
3. 3.

   A PVC chain has 600 repeat units, each C₂H₃Cl with a mass of 62.5 g/mol. What is the chain's molar mass, Esme?
4. 4.

   Hammered copper flattens, but a hammered salt crystal shatters. Which structural idea explains the difference, Jun?

   • Salt particles are lighter than copper atoms, so a hammer breaks them apart more easily
   • Metal layers slide while shared electrons hold them; sliding salt ions meet like charges
   • Copper has no bonds between its atoms, so its layers can flow like a liquid under a hammer
5. 5.

   Graphite and diamond are both pure carbon, but only graphite conducts. Why, Luz?

   • Diamond atoms have no electrons of their own, so no electrons are available to carry current
   • Graphite has layers with free electrons; diamond's electrons are locked in bonds
   • Graphite has a little metal mixed in, while diamond has no metal inside it
6. 6.

   Eggs slide off a PTFE-coated pan. What best explains it, Milo?

   • PTFE atoms carry a strong charge that pushes food away from the pan's surface
   • Fluorine atoms around the carbon chains attract other molecules weakly, so little sticks
   • PTFE slowly melts a thin layer of its own oil, and the food slides on that oil layer
7. 7.

   A copper wire is coated with plastic. Why does the plastic stop the current, Pia?

   • The plastic is thick enough that electrons cannot squeeze through
   • The plastic repels electrons because it is charged negatively
   • Its electrons stay in bonds, so none are free to carry current

8. Read this first

   Wire coating scores (example scores, 1 to 5)

   material	flexibility	insulation	low cost
   PVC plastic	4	5	4
   natural rubber	5	5	2
   copper	3	1	3

9. 8.

   A coating needs an insulation score of at least 4 and a low-cost score of at least 3. Which material passes, Ren?

   • PVC plastic only, since rubber's cost score is 2
   • Natural rubber only, since it is the most flexible
   • PVC plastic and natural rubber, which both insulate well
10. 9.

    A coating needs an insulation score of at least 4 and a total of at least 12. Which materials pass, Tala?

    • PVC plastic alone, since rubber's total of 12 cannot beat PVC's 13
    • PVC plastic and natural rubber, with totals of 13 and 12
    • Neither material, since a total of 12 is not above the limit of 12
11. 10.

    Flexibility now counts triple, and the other two criteria count once. Which material has the highest total, Zee?

    • Copper, since its flexibility counts triple
    • Natural rubber, with 22 against PVC's 21
    • PVC plastic, the winner with 13 against 12 before weighting