PIMSO 2025 - Science - Secondary 2 - National Round Question 8

Question 8

Different metals react differently with oxygen, water and dilute acid, allowing a reactivity series to be deduced. In a reaction with oxygen, why does iron fillings rust faster than iron nail?
Editorial comparison: equal amounts of iron, similar temperature and exposure.

The iron fillings contain more atoms than an iron nail.
The iron fillings are hotter than iron nail.
The iron fillings weighs heavier than an iron nail.
The iron fillings have bigger surface area than the iron nail.