Forces between molecules and boiling points

Answer Key - Grade 10 Science Worksheet - Challenge Me

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

1. 1.

   Water boils at 100 °C and hydrogen sulfide at -60.33 °C. In kelvins, how many times higher is water's boiling point, to 0.01, Ari?

   1.75 times
2. 2.

   Ammonia boils at -33.35 °C and methane at -161.5 °C. In kelvins, how many times higher is ammonia's boiling point, to 0.01, Bo?

   2.15 times
3. 3.

   Why can a paper clip rest on the surface of still water, Jun?

   • Hydrogen bonds give surface tension
   • The paper clip is lighter than the air
   • Water repels metal
4. 4.

   Why does ice float, in terms of attractions, Kira?

   • Ice has no attractions
   • Dispersion is strongest in ice crystals
   • Hydrogen bonds hold an open pattern
5. 5.

   Why don't oil and water mix, Luz?

   • Oil is ionic
   • Each attracts its own kind more
   • Water is nonpolar
6. 6.

   Milo says boiling water splits it into hydrogen and oxygen. Agree or disagree?

   • Disagree: molecules stay whole
   • Agree: heat breaks the O–H bonds
   • Agree: steam is H and O
7. 7.

   Noah says melting ice breaks the covalent bonds in each water molecule. Agree or disagree?

   • Agree: ice is made of atoms
   • Disagree: only attractions loosen
   • Agree: covalent bonds melt first
8. 8.

   Which boils higher, NH₃ or H₂S, Ren?

   • NH₃
   • H₂S
   • They boil at the same point
9. 9.

   Which boils higher, Cl₂ or Br₂, Tala?

   • They boil at the same point
   • Cl₂
   • Br₂
10. 10.

    Which lists CH₄, NH₃ and H₂O from lowest to highest boiling point, Zee?

    • CH₄, NH₃, H₂O
    • H₂O, NH₃, CH₄
    • NH₃, CH₄, H₂O