The four states of matter and particle motion

Answer Key - Grade 10 Science Worksheet - Challenge Me

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

1. 1.

   Ari turns 10 g of ice at −10 °C into steam at 100 °C. Specific heats: ice 2.09, water 4.18 J/g/°C. Melting 334 J/g, boiling 2260 J/g. Total joules?

   30,329 J
2. 2.

   Bo turns 5 g of ice at −20 °C into steam at 100 °C. Specific heats: ice 2.09, water 4.18 J/g/°C. Melting 334 J/g, boiling 2260 J/g. Total joules?

   15,269 J
3. 3.

   Esme turns 20 g of ice at −5 °C into steam at 100 °C. Specific heats: ice 2.09, water 4.18 J/g/°C. Melting 334 J/g, boiling 2260 J/g. Total joules?

   60,449 J
4. 4.

   10.0 g of steam and 10.0 g of boiling water, both at 100 °C, cool to 40 °C on skin. Steam condenses at 2260 J/g; water cools at 4.18 J/g/°C. Which releases more, Jun?

   • Steam, about 10 times as much: 22,600 J from condensing, 2,508 J from cooling
   • Steam, but just slightly more, because steam is a gas with a very low density here
   • The same, because both start at 100 °C and both end at 40 °C on the skin
5. 5.

   Kira drops 20.0 g of ice at 0 °C into 200 g of water at 25 °C. Melting takes 334 J/g; water 4.18 J/g/°C. What is the final temperature?

   • About 12.5 °C, the simple average of the two starting temperatures, 0 °C and 25 °C
   • About 15.5 °C, after the water melts the ice and warms the meltwater
   • About 22.7 °C, found by skipping the energy needed to melt the ice
6. 6.

   Dry ice (solid CO₂) turns straight to gas at 1 atm and never forms a puddle. CO₂'s triple point is 5.1 atm. Why no liquid, Luz?

   • Dry ice is so cold that no liquid can form at any pressure whatever
   • Liquid CO₂ needs more than 5.1 atm; at 1 atm the solid goes straight to gas
   • CO₂ molecules are too light to stay together as a liquid anywhere on Earth
7. 7.

   Noah says a tub of 30 °C water holds less thermal energy than a cup of 60 °C water, since 60 is hotter. Verdict?

   • Wrong: both are water, so the two samples hold equal amounts of thermal energy
   • Right: a higher temperature always means more thermal energy in a sample
   • Not necessarily: temperature is only an average, and the tub has far more particles
8. 8.

   CO₂ at 50 atm and 300 K does not follow the ideal gas model well. Which reason fits the particle model, Pia?

   • The molecules slow almost to a stop when the pressure gets that high
   • The molecules shrink at high pressure, which leaves them even more gaps
   • The molecules are crowded, so their own volume and attractions matter
9. 9.

   NH₃ (17.0 u) and HCl (36.5 u) gases start from opposite ends of a long tube at one temperature. Where does white NH₄Cl form, Ren?

   • Closer to the NH₃ end, since ammonia is the more reactive gas
   • Closer to the HCl end, since lighter NH₃ moves about 1.5 times as fast
   • At the midpoint, since both gases carry the same average kinetic energy
10. 10.

    In a sealed jar at 25 °C, water and its vapor are in equilibrium. What does that mean, Zee?

    • Evaporation keeps running faster than condensation until the water is gone
    • Evaporation has stopped, so the jar holds just still water
    • Molecules evaporate and condense at equal rates, so amounts stay steady