Question

which of the following is a chemical change?
a) boiling water
b) dissolving sugar in water
c) burning paper
d) breaking a glass

when wood burns, it produces ash, heat, and light. this is an example of a...
a) physical change
b) chemical change
c) phase change
d) reversible change

which of the following is an example of a substance in the gas state?
a) ice
b) water vapor
c) mercury
d) sand

which phase change occurs when a liquid turns into a gas?
a) condensation
b) melting
c) evaporation
d) freezing

Explanation:

1. Boiling water is a physical change of state from liquid to gas without forming new substances. Dissolving sugar in water is a physical process of sugar dispersing in water without new - substance formation. Breaking a glass is just a change in the physical shape of the glass. Burning paper involves a chemical reaction with oxygen to form new substances like carbon dioxide and ash, so it is a chemical change.
2. When wood burns, new substances such as ash are produced along with the release of heat and light, which is characteristic of a chemical change.
3. Ice is in the solid state, mercury is a liquid at room temperature, sand is a solid. Water vapor is water in the gas state.
4. Condensation is the change from gas to liquid, melting is from solid to liquid, freezing is from liquid to solid. Evaporation is the process of a liquid turning into a gas.

Answer:

1. c) Burning paper
2. b) Chemical change
3. b) Water vapor
4. c) Evaporation