Question

what do these two changes have in common? a dinosaur bone turning into rock over millions of years newly poured concrete becoming hard select all that apply. both are changes of state. both are caused by heating. both are chemical changes. both are only physical changes.

Explanation:

A dinosaur bone turning into rock is fossilization (a chemical - geological process), and concrete hardening is a chemical reaction between cement and water. Neither is just a physical change or a change of state not caused by heating in the relevant sense here. Both involve chemical reactions at a fundamental level.

Answer:

C. Both are chemical changes.