Why salt, sugar and copper behave differently

Answer Key - Grade 10 Science Worksheet

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

1. 1.

   Table salt's density is 2.17 g/cm³ (CRC). What is the mass of a 3 cm³ salt crystal, Ari?

   6.51 g
2. 2.

   Sugar's density is 1.5805 g/cm³ (CRC). What is the mass of a 2.5 cm³ sugar cube, to 0.01 g, Bo?

   3.95 g
3. 3.

   Copper's density is 8.933 g/cm³ (PubChem). What is the mass of a 1.5 cm³ copper block, to 0.01 g, Esme?

   13.4 g
4. 4.

   Why does salt need a much higher temperature to melt than sugar, Jun?

   • Ionic attractions are strong
   • Salt crystals are larger than sugar's
   • Sugar is a metal
5. 5.

   When sugar melts, what is pulled apart, Kira?

   • Sodium and chloride ions
   • Whole sugar molecules
   • The atoms inside each molecule
6. 6.

   Why does copper melt only above 1000 °C, Luz?

   • It has no electrons
   • Its molecules are heavy
   • Its electron sea holds ions strongly
7. 7.

   Why does salt water conduct electricity, Milo?

   • Its dissolved ions can move
   • Water molecules carry current
   • Any solution conducts
8. 8.

   Salt is melted at 800.7 °C. Does the liquid conduct, Pia?

   • No: it is still salt
   • No: liquids can't conduct
   • Yes: its ions are free
9. 9.

   A solid melts above 700 °C, shatters and conducts only when dissolved. What bonding does it likely have, Ren?

   • Covalent molecules
   • Metallic
   • Ionic
10. 10.

    A solid melts below 200 °C and doesn't conduct even when dissolved. What bonding does it likely have, Zee?

    • Ionic
    • Metallic
    • Covalent molecules