The diagrams below illustrate two different experiments. Experiment 1 involves testing for a gas, and experiment 2 involves determining the relative density of wood. For experiment 1, identify the gas

1. The diagrams below illustrate the steps a student used to test for oxygen gas.

• a) Name the gas being tested for. The gas being tested for is oxygen gas.

• b) State the purpose of:

  • i) Adding manganese(IV) oxide in step II. The purpose of adding manganese(IV) oxide ($\text{MnO}_2$) is to act as a catalyst to speed up the decomposition of hydrogen peroxide.
  • ii) Testing the gas with a glowing splint in step IV. The purpose of testing the gas with a glowing splint is to confirm the presence of oxygen gas, as oxygen rekindles a glowing splint.

• c) State the observation in step IV and the conclusion drawn from it.

  • Observation: The glowing splint rekindles (bursts into flame).
  • Conclusion: The gas collected is oxygen.

2. In determining the relative density of a piece of wood, it is first weighed in air, and then in water as illustrated in the diagrams below.

• a) Read and record:

  • i) Weight ($\text{W}_1$) of the wood in air. $$\text{W}_1 = \boxed{\text{2 N}}$$
  • ii) Weight ($\text{W}_2$) of the wood in water. $$\text{W}_2 = \boxed{\text{1 N}}$$

• b) Calculate:

  • i) Apparent loss of weight of the wood in water.