Question

grade/element:
date:
dr. jassal
questions 26 - 35: label each of the following phase changes as melting (m), freezing (f), evaporation (e), condensation (c), sublimation (s) and deposition (d). the options can be used more than once.
26.____steel is an alloy of metal and iron. when it is exposed to temperatures above 1370°c it transitions to a liquid.
27.____you are working in the laboratory wearing goggles. often, the goggles start to fog up. the gaseous water inside the goggles becomes liquid.
28.____in sub - freezing air, water vapor changes directly to ice.
29.____liquid water is exposed to low temperatures below 0°c and transitions to a solid.
30.____dry ice is solid carbon dioxide (co₂). it is used to keep samples cold in a laboratory. when dry ice is left out at room temperature it turns to gas.
31.____a puddle on the ground is exposed to temperatures above 100°c, and the water transitions to a gas state.
32.____naphthalene, an organic compound commonly found in pesticides such as mothballs, is a solid. at high pressures the solid form of naphthalene turns into gas.
33.____on a hot day you are playing football outside and sweat forms. when the sweat transitions from liquid to gas, this cools your body down.
34.____in forensic science, iodine fuming is a method to visualize fingerprints. solid iodine is exposed to heat and it turns into gas, which reveals invisible fingerprints.
35.____a glass of ice water forms water droplets on the outside. gaseous water cools to become liquid.

1. phase changes occur due to changes in heat or ____.

a. time
b. light
c. pressure
d. sound

Explanation:

Step1: Identify phase - change definitions

Melting is solid to liquid, freezing is liquid to solid, evaporation is liquid to gas, condensation is gas to liquid, sublimation is solid to gas, and deposition is gas to solid.

Step2: Analyze question 26

Steel transitions from solid to liquid above 1370°C, so it is melting (M).

Step3: Analyze question 27

Gaseous water in goggles becomes liquid, so it is condensation (C).

Step4: Analyze question 28

Water vapor changes directly to ice in sub - freezing air, so it is deposition (D).

Step5: Analyze question 29

Liquid water transitions to solid below 0°C, so it is freezing (F).

Step6: Analyze question 30

Dry ice (solid CO₂) turns to gas at room temperature, so it is sublimation (S).

Step7: Analyze question 31

Water in a puddle transitions to gas above 100°C, so it is evaporation (E).

Step8: Analyze question 32

Solid naphthalene turns into gas at high pressures, so it is sublimation (S).

Step9: Analyze question 33

Sweat transitions from liquid to gas, so it is evaporation (E).

Step10: Analyze question 34

Solid iodine turns into gas when exposed to heat, so it is sublimation (S).

Step11: Analyze question 35

Gaseous water cools to become liquid on the outside of a glass of ice - water, so it is condensation (C).

Step12: Analyze question 36

Phase changes occur due to changes in heat or pressure. The answer is C.

Answer:

1. M
2. C
3. D
4. F
5. S
6. E
7. S
8. E
9. S
10. C
11. C. pressure