Practical Skills

• What is the independent variable in an experiment?


  The variable that the investigator deliberately changes.
• What is the dependent variable?


  The variable that changes when the independent variable is changed.
• What are control variables?


  Variables that must be kept constant or monitored to ensure valid results.
• What is a hypothesis?


  A prediction about what will happen in an experiment.
• What does the term 'range' refer to in an experiment?


  The minimum to maximum value of a variable.
• Why is it important to choose a suitable range in an experiment?


  A suitable range ensures that the full pattern can be observed, making results valid.
• What is an interval in the context of data collection?


  The gap between readings in an experiment.
• What problem arises if intervals are too large in an experiment?


  The pattern might change between measurements, leading to missed data.
• What does it mean for a method to be valid?


  A valid method can effectively answer the question being investigated.
• How does calibration affect measurements?


  Calibration ensures that a measuring instrument measures correctly.
• What is resolution in the context of measuring instruments?


  The smallest change that a measuring instrument can measure.
• What does it mean for a result to be accurate?


  A result is accurate if it is close to the true value.
• Can a measurement be precise but not accurate?


  Yes, precision refers to closeness to the mean, while accuracy refers to closeness to the true value.
• What is an anomaly in experimental results?


  An odd result that does not fit the pattern, caused by a random error.
• What causes random errors in measurements?


  Random errors are unpredictable and can be caused by mistakes made by the experimenter.
• How can we reduce the impact of random errors in experiments?


  By repeating readings, comparing results, and calculating the mean while excluding anomalies.
• What are systematic errors?


  Errors that are consistent each time, often caused by the environment, method, or equipment.
• What is a zero error?


  A zero error occurs when a measuring instrument does not read zero when nothing is being measured.
• How can you avoid systematic errors in measurements?


  By using measuring equipment correctly, calibrating instruments, and changing the method if necessary.
• What does it mean for an experiment to be repeatable?


  It means the same person can repeat the experiment with the same method and equipment and get the same results.
• What does it mean for an experiment to be reproducible?


  It means the experiment can be repeated by a different person or with different methods and still yield the same results.
• What is uncertainty in measurements?


  Uncertainty indicates how much doubt there is in a measurement.
• How do we calculate uncertainty?


  Uncertainty is half the range of the measurements.
• What is the uncertainty for the volumes measured: 124, 126, 123, 125, 123 cm³?


  The uncertainty is $1.5 \text{ cm}^3$.
• How can we improve accuracy in measurements?


  By reducing errors and uncertainty, using higher resolution instruments, and taking repeats to calculate a mean.
• What are the differences between continuous data and categoric data?


  • Continuous data: Numerical values (e.g., height).
  • Categoric data: Word labels (e.g., eye color).
• What type of graph should be used for continuous data?

  A line graph.
• What type of graph should be used for categoric data?


  A bar chart.
• What is the use of a gas syringe?


  To measure the volume of gas in centimetres cubed (cm³).
• What is the use of a measuring cylinder?


  To measure the volume of liquid or solution in centimetres cubed (cm³).
• What is the use of an electronic balance?


  To measure mass in grams (g).
• What is the use of a stopwatch?


  To measure time in minutes (mins), seconds (s), or hours (h).
• What is the use of a thermometer?


  To measure temperature in degrees Celsius (°C).
• What is the use of a metre rule?


  To measure length in centimetres (cm) or millimetres (mm).
• What is the use of a micrometer?


  To measure small lengths or diameters in millimetres (mm).
• What is the use of a voltmeter?


  To measure potential difference in volts (V).
• What is the use of an ammeter?


  To measure current in amps (A).
• What is the use of a joulemeter?


  To measure energy in joules (J).
• What is the purpose of a conical flask?


  To mix solutions while preventing splashing due to its narrow neck.
• What is the purpose of a beaker?


  To mix, hold, or collect liquids, but not for precise measurements.