Question

question 6 (1 point)
listen
which one of these represents a chemical change?
a) cutting a bar of sodium metal into pieces with a knife
b) turning hair yellow with bleach
c) boiling water to form steam
d) melting butter
e) mixing powdered charcoal and oxygen at room temperature
question 7 (1 point)
listen
of the following, select all that represent a chemical change?
a) boiling an egg.
b) chopping wood.
c) burning gasoline.
d) melting candle wax.
e) demagnetizing metals (as is done with common anti - theft security tags).

Explanation:

For Question 6:

A chemical change produces new substances, while physical changes only alter form/state.

• a) Cutting sodium is physical (no new substance).
• b) Bleach reacts with hair pigments to break chemical bonds, forming new colorless compounds (chemical change).
• c) Boiling water is a state change (physical).
• d) Melting butter is a state change (physical).
• e) Charcoal and oxygen only react when heated; mixing at room temp is physical.

For Question 7:

• a) Boiling an egg denatures proteins, changing their chemical structure (chemical change).
• b) Chopping wood only changes size (physical).
• c) Burning gasoline reacts with oxygen to form CO₂, water, and other new substances (chemical change).
• d) Melting wax is a state change (physical).
• e) Demagnetizing metals only alters magnetic properties (physical).

Answer:

Question 6: b) Turning hair yellow with bleach
Question 7:
a) Boiling an egg.
c) Burning gasoline.