Question

what do these two changes have in common? dust settling out of the air building a tower out of magnetic blocks select all that apply. both are changes of state. both are only physical changes. both are caused by heating. both are chemical changes. submit work it out

Explanation:

1. Analyze "dust settling out of the air": This is a physical change as dust particles are just moving from air to a surface, no new substance is formed, and it's not a change of state (dust is solid, air has it suspended, settling is just position change) nor caused by heating.
2. Analyze "building a tower out of magnetic blocks": This is a physical change as we're just arranging blocks, no new substance, not a change of state (blocks remain solid), and not caused by heating.
3. Evaluate options:

• "Both are changes of state": Incorrect, neither is a state change (solid - liquid - gas change).
• "Both are only physical changes": Correct, both involve physical rearrangement without new substances.
• "Both are caused by heating": Incorrect, neither process is caused by heating.
• "Both are chemical changes": Incorrect, no chemical reactions (no new substances) occur.

Answer:

Only the option "Both are only physical changes" is correct. So the correct option is: Both are only physical changes.