A laboratory experiment requires each student to use 10g of caustic soda (NaOH). A laboratory personnel opens a new 909g of said salt. If 42 students took exactly the required amount of salt, how much should be left in the container at the end of the experiment?
Correct answer: D. 0.489 kg
- A. 1.07 kg
- B. 48.9 g
- C. 0.897 g
- D. 0.489 kg
Explanation
Each student requires 10 g of NaOH, therefore, the total amount of NaOH required for 42 students is:10 g/student x 42 students = 420 gThe initial amount of NaOH in the container is 909 g. Therefore, the amount of NaOH left after the experiment is:909 g - 420 g = 489 gConverting grams to kilograms:489 g = 0.489 kgTherefore, the correct answer is D) 0.489 kg
This question appeared on the NUMS 2019 (cancelled sitting) paper, which you can sit online with every answer explained.
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