Question

what do these two changes have in common?
a dinosaur bone turning into rock over millions of years
bleaching hair
select all that apply.
both are only physical changes.
both are changes of state.
both are caused by cooling.
both are chemical changes.
submit

Explanation:

1. Analyze "a dinosaur bone turning into rock (fossilization)": This is a chemical change as the organic material in the bone is replaced by minerals, forming a new substance (rock - like fossil). It is not a change of state (state changes are like solid - liquid - gas) and not caused by cooling. It is not a physical change (physical changes don't form new substances).
2. Analyze "bleaching hair": Bleaching hair involves a chemical reaction where the hair's pigment is altered (new substances are formed in the hair structure), so it is a chemical change. It is not a change of state, not caused by cooling, and not a physical change.
3. So the only correct option among the given ones is "Both are chemical changes" because both processes result in the formation of new substances (a key characteristic of chemical changes). The other options are incorrect: "Both are only physical changes" is wrong as both are chemical; "Both are changes of state" is wrong as they don't involve state (solid/liquid/gas) change; "Both are caused by cooling" is wrong as neither process is driven by cooling.

Answer:

The correct option is: Both are chemical changes.