Figure 7 shows a piece of sodium being added to water. Give two observations that could be seen when sodium is added to water.

When sodium reacts with water, a vigorous chemical reaction occurs: 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g). The observations are:\n1. **Fizzing/Bubbles:** Hydrogen gas is produced, which is seen as fizzing or effervescence.\n2. **Movement:** The sodium darts around on the surface of the water, pushed by the hydrogen gas being produced.\n3. **Melting:** The reaction is very exothermic (releases a lot of heat), which is enough to melt the sodium (melting point 98°C) into a silvery ball.\n4. **Disappearing/Dissolving:** The sodium is used up in the reaction, forming colourless sodium hydroxide solution, so it appears to dissolve or disappear.