Why water matters for life: cohesion, adhesion, heat and ice

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Ari studies a water molecule drawn as beads. Bead X is the oxygen. What charge does the oxygen end of a water molecule carry?

   • A slightly positive charge
   • A full negative charge, like an ion
   • A slightly negative charge
   • No charge, because water is nonpolar

2. Read this first

   Use this

   Two water molecules drawn as beads, not to scale. Molecule 1: an oxygen bead joined by solid lines to two hydrogen beads. Molecule 2: the same. A dashed line joins one hydrogen bead of molecule 1 to the oxygen bead of molecule 2. Beads are lettered: X is the oxygen of molecule 1, Y is the hydrogen of molecule 1 that has the dashed line, Z is the oxygen of molecule 2, and W is a hydrogen of molecule 2.

3. 2.

   Bo labels beads in the drawing. Which two beads are joined by a hydrogen bond?

   • Y and Z
   • Z and W
   • X and Y
   • X and W
4. 3.

   Esme asks why two water molecules in the drawing attract each other. Which reason is right?

   • Water is nonpolar, so neighbors pull on each other evenly
   • Like charges on neighboring molecules pull them together
   • Covalent bonds join each molecule to the next one
   • Slightly positive hydrogens are drawn to slightly negative oxygens
5. 4.

   A drop on Jun's desk keeps a round dome. Its water molecules are attracted to other water molecules. What is that attraction called?

   • Evaporation
   • Capillary action
   • Adhesion
   • Cohesion

6. Use this

   not to scale.

7. 5.

   Water clings to the side of Kira's drinking glass. The attraction is between water molecules and the glass. What is it called?

   • Cohesion
   • Specific heat
   • Adhesion
   • Surface tension
8. 6.

   Luz reads that ice floats because it is less dense than liquid water. What does less dense mean?

   • Fewer molecules in the same space
   • A lower freezing temperature
   • A larger total mass
   • More molecules in the same space
9. 7.

   After a game, Noah feels cooler as sweat dries in the breeze. Why does drying sweat cool the skin?

   • The skin soaks up the cold from the sweat
   • The sweat blocks heat from the Sun
   • The sweat is colder than the air around it
   • The evaporating water takes heat from the skin
10. 8.

    Not to scale. Pia compares two cases. Which one shows adhesion, and why?

    • Case 1, because water molecules hold together
    • Case 2, because water is attracted to the paper
    • Case 2, because water molecules hold together
    • Neither case, because both come from heat

11. Use the table

    Material	Start (°C)	After 5 minutes (°C)
    water	18	21
    sand	18	33

    model data, equal masses of 250 g each under the same lamp.

12. 9.

    Tala reads the table. By how many °C did the water's temperature rise?

    • 21 °C
    • 18 °C
    • 3 °C
    • 15 °C
13. 10.

    Water has a high specific heat. Zee predicts what that means for water compared with sand under the same lamp. Which prediction is right?

    • The water warms more slowly
    • The water ends up hotter
    • The water warms faster
    • The water stays at one temperature