Question 1:
Chemicals are substances that cannot be ignored in our daily lives.
(a) State five types of chemicals that are commonly used in daily life.
(b) For each chemical stated in (a), state its use.
Answer:
(a) Salt, sugar, paint, preservative, detergent (any other acceptable answers).
(b)
Salt – as flavouring agent or preservative.
Sugar – as flavouring agent or preservative
Paint – used to paint buildings, wood or metal as protection
Preservative – to preserve food so that it can be kept for a longer period
Detergent – used as cleaning agent to remove dirt from clothes
(any other acceptable answers).
Chemicals are substances that cannot be ignored in our daily lives.
(a) State five types of chemicals that are commonly used in daily life.
(b) For each chemical stated in (a), state its use.
Answer:
(a) Salt, sugar, paint, preservative, detergent (any other acceptable answers).
(b)
Salt – as flavouring agent or preservative.
Sugar – as flavouring agent or preservative
Paint – used to paint buildings, wood or metal as protection
Preservative – to preserve food so that it can be kept for a longer period
Detergent – used as cleaning agent to remove dirt from clothes
(any other acceptable answers).
Question 2:
(a) Name three industries in Malaysia that use knowledge of chemistry.
(b) How do the industries stated in (a) benefit our country?
Answer:
(a) Agricultural industry, cosmetics industry, medical industry (any other acceptable answers).
(b)
Agriculture – provides source of food and income to the country
Cosmetics – provides source of income to the country
Medicine – provides new medicines to the people and improve their quality of life
(any other acceptable answers).
(a) Name three industries in Malaysia that use knowledge of chemistry.
(b) How do the industries stated in (a) benefit our country?
Answer:
(a) Agricultural industry, cosmetics industry, medical industry (any other acceptable answers).
(b)
Agriculture – provides source of food and income to the country
Cosmetics – provides source of income to the country
Medicine – provides new medicines to the people and improve their quality of life
(any other acceptable answers).
Question 3:
List out three types of personal protective equipment and state the function of each equipment.
Answer:
Safety glasses – used to prevent dust or chemicals from splashing into the eyes
Laboratory coat – used to protect the body and clothes from chemical spills such as acid, alkali and organic solvent
Gloves – used when handling chemicals to protect the hands from injury, chemicals or infections
(any other acceptable answers)
List out three types of personal protective equipment and state the function of each equipment.
Answer:
Safety glasses – used to prevent dust or chemicals from splashing into the eyes
Laboratory coat – used to protect the body and clothes from chemical spills such as acid, alkali and organic solvent
Gloves – used when handling chemicals to protect the hands from injury, chemicals or infections
(any other acceptable answers)
Question 4:
Complete the following flow chart on the steps involved in a scientific method.
Answer:
Making observations ➞ Making an inference ➞ Identifying the problem ➞ Making a hypothesis ➞ Identifying variables ➞ Controlling the variables ➞ Planning the experiment ➞ Collecting data ➞ Interpreting data ➞ Making a conclusion ➞ Writing a report.
Complete the following flow chart on the steps involved in a scientific method.
Answer:
Making observations ➞ Making an inference ➞ Identifying the problem ➞ Making a hypothesis ➞ Identifying variables ➞ Controlling the variables ➞ Planning the experiment ➞ Collecting data ➞ Interpreting data ➞ Making a conclusion ➞ Writing a report.
Question 5:
State the safety measures that should be taken to overcome mercury spill accidents that occur in the school laboratory.
Answer:
Precautionary steps to be taken:
1. Inform the teacher or laboratory assistant immediately about the accident.
2. Mark the spillage area as a restricted zone.
3. Sprinkle sulphur powder to cover the spillage
4. Contact the Fire and Rescue Department for further action.
State the safety measures that should be taken to overcome mercury spill accidents that occur in the school laboratory.
Answer:
Precautionary steps to be taken:
1. Inform the teacher or laboratory assistant immediately about the accident.
2. Mark the spillage area as a restricted zone.
3. Sprinkle sulphur powder to cover the spillage
4. Contact the Fire and Rescue Department for further action.
Question 6:
Three pieces of cloth with a size of 10 cm × 10 cm each are sprinkled with 20 cm3 of distilled water. Then, all the three pieces of cloth are folded in different styles and left to dry at room temperature. The time taken for each piece to dry is recorded.
(a) Explain why the three pieces of cloth are folded in different styles.
(b) Suggest a hypothesis for this experiment.
(c) Make an inference for this experiment.
(d) Determine the variables involved in this experiment.
(e) Construct a suitable table to record the readings in this experiment.
Answer:
(a) To give a different surface area for the cloth.
(b) The larger the surface area of the cloth, the faster the cloth will dry.
(c) Cloth with larger surface area will dry faster than cloth with smaller surface area.
(d)
Manipulated variable: Surface area of cloth
Responding variable: Rate of drying of cloth
Fixed variable: Surrounding temperature, type of cloth used, size of cloth
(e)
Three pieces of cloth with a size of 10 cm × 10 cm each are sprinkled with 20 cm3 of distilled water. Then, all the three pieces of cloth are folded in different styles and left to dry at room temperature. The time taken for each piece to dry is recorded.
(a) Explain why the three pieces of cloth are folded in different styles.
(b) Suggest a hypothesis for this experiment.
(c) Make an inference for this experiment.
(d) Determine the variables involved in this experiment.
(e) Construct a suitable table to record the readings in this experiment.
Answer:
(a) To give a different surface area for the cloth.
(b) The larger the surface area of the cloth, the faster the cloth will dry.
(c) Cloth with larger surface area will dry faster than cloth with smaller surface area.
(d)
Manipulated variable: Surface area of cloth
Responding variable: Rate of drying of cloth
Fixed variable: Surrounding temperature, type of cloth used, size of cloth
(e)