Laboratory equipment and basic practical skills: แบบฝึกหัด

When conducting experiments in a school laboratory, what is the standard International System of Units (SI) unit for measuring time?

During a scientific investigation, a student records the temperature of a liquid every minute for 10 minutes. According to the science process skills, which category does the act of using a thermometer and writing down the numbers fall into?

A student is preparing to heat a small volume of a liquid chemical in a test tube using a Bunsen burner. Which of the following practices is not considered a correct and safe procedure for this activity?

A student is using a Bunsen burner to heat water in a beaker. To achieve uniform heating and prevent the beaker from cracking due to direct flame contact, which combination of apparatus must be used to support the beaker?

A student is using a thermometer with a scale ranging from \(-10 ^\circ\text{C}\) to \(110 ^\circ\text{C}\). If the smallest division on the scale is \(1 ^\circ\text{C}\), which of the following is the most appropriate way to record a temperature that appears exactly halfway between 32 and 33?

What is the primary reason for thoroughly washing all laboratory glassware immediately after completing an experiment?

A student is using a measuring cylinder to determine the volume of a liquid. To obtain an accurate reading, where should the student's eye level be positioned relative to the liquid surface, and which specific part of the meniscus should be read?

State one important safety precaution that must be observed when heating a liquid in a test tube.

A student is tasked with accurately determining the boiling point of a small volume of a liquid known to be flammable, such as ethanol ($$C_2H_5OH$$). Precision and safety are paramount for this experiment.

(a) Describe a complete and safe experimental setup, identifying all necessary laboratory apparatus, for conducting this experiment. Include details on how the apparatus should be arranged to ensure accurate temperature measurement and safe heating of the flammable liquid.
(b) Explain two critical safety precautions that must be observed during the heating process, specifically considering the flammable nature of the liquid.
(c) Discuss two potential sources of error that could affect the accuracy of the measured boiling point, differentiating between random and systematic errors if applicable. For each error, suggest a practical method to minimise its impact.