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.

   Iodine boils at 184.4 °C and fluorine at -188.12 °C. In kelvins, how many times higher is iodine's boiling point, to 0.01, Esme?

   5.38 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 don't oil and water mix, Luz?

   • Oil is ionic
   • Each attracts its own kind more
   • Water is nonpolar
5. 5.

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

   • Agree: steam is H and O
   • Disagree: molecules stay whole
   • Agree: heat breaks the O–H bonds
6. 6.

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

   • Disagree: only attractions loosen
   • Agree: covalent bonds melt first
   • Agree: ice is made of atoms
7. 7.

   Pia says a hydrogen bond is the bond inside H₂ gas. Agree or disagree?

   • Agree: any bond to H counts
   • Agree: H₂ has a hydrogen bond
   • Disagree: it joins two molecules
8. 8.

   Which boils higher, NH₃ or H₂S, Ren?

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

   Which boils higher, Cl₂ or Br₂, Tala?

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

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

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