Question 1:
Figure 1 shows several examples of waste substances in the school laboratory.
(a) Based on Figure 1, list out wastes that cannot be disposed of into the school sink or the rubbish bin.
(b) Explain how to manage the waste substances listed in (a) correctly.
Answer:
(a) Used gloves, broken conical flask, bromine, concentrated acid
(b) Gloves and conical flask – must be thrown into a special container
Bromine – must be stored in a covered container away from light and heat source
Concentrated acid – must be put in a labelled container and disposed
Figure 1 shows several examples of waste substances in the school laboratory.
(a) Based on Figure 1, list out wastes that cannot be disposed of into the school sink or the rubbish bin.
(b) Explain how to manage the waste substances listed in (a) correctly.
Answer:
(a) Used gloves, broken conical flask, bromine, concentrated acid
(b) Gloves and conical flask – must be thrown into a special container
Bromine – must be stored in a covered container away from light and heat source
Concentrated acid – must be put in a labelled container and disposed
Question 2:
Halim is a farmer. He plants various types of vegetables to supply the local market. However, lately, Halim realised that the produce was unsatisfactory and the growth of vegetables was stunted, or the vegetables had died off. He suspected the soil to be acidic. As a scientist, you are asked to help Halim to determine the most suitable pH value of the soil for planting vegetables. Suggest a suitable hypothesis and state briefly how you can control the variables in this experiment.
Answer:
(Student’s suitable answer)
Hypothesis: Soil with acidic pH is not suitable to plant vegetables
Method to control:
Manipulated variable: Type of soil // neutral soil, acidic soil and alkaline soil
Responding variable: Rate of growth of vegetables in soil of different pH
Fixed variable: Type of vegetable, same light intensity
Halim is a farmer. He plants various types of vegetables to supply the local market. However, lately, Halim realised that the produce was unsatisfactory and the growth of vegetables was stunted, or the vegetables had died off. He suspected the soil to be acidic. As a scientist, you are asked to help Halim to determine the most suitable pH value of the soil for planting vegetables. Suggest a suitable hypothesis and state briefly how you can control the variables in this experiment.
Answer:
(Student’s suitable answer)
Hypothesis: Soil with acidic pH is not suitable to plant vegetables
Method to control:
Manipulated variable: Type of soil // neutral soil, acidic soil and alkaline soil
Responding variable: Rate of growth of vegetables in soil of different pH
Fixed variable: Type of vegetable, same light intensity