David observed properties of four different compounds, only
one of which is an ionic compound. His observations are
shown in the chart.
Compound
W
Observations
Is a hard solid, melts
at 44° C, has a
molecular structure
Is a brittle solid, does
not conduct
electricity in water.
has a crystal
structure
Is a hard solid
conducts electricity.
has a molecular
structure
Is a brittle solid,

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e