14 The mass of an empty watch glass was 70521 g When a scoop

14. The mass of an empty watch glass was 70.521 g. When a scoopful of sodium bicarbonate was added to that watch glass, the mass was increased to 72.539g. What was the mass of the sodium bicarbonate added to the watch glass? (a)41.539 g (c) None of the above (b) 1.018 g d)-1.018 15. Which of the following ac ons are appropriate of your clothing catches on fire? (a) Stop, drop&roll; (b) Use the safety shower to ex nguish the flames (c) Use a fire blanket to smother the flames (d) All of these 16. Experimentally, a student finds that the percent error is 25.0 %. She forgot to write down the accepted value for her density, but remembered, her experimental density value, which was 8.69g/mL (b) 4.80 g/mL (a) 6.95 g/mL (d) 1.24 g/ml (c)8.00 g/ml 17. What must you do before or at the end of every class? (a) Write a paragraph about what you read from the Background & Introduc on in your manual (b) Complete Pre-Lab/Post-Lab on Eleam (c) Complete Pre-Lab In Class Quiz (d) All of the above

Solution

14) mass of sodium bicarbonate = (mass of watchglass+ mass sodium bicarbonate) - mass of watchglass

Mass of sodium bicarbonate = 72.539 g - 70.521 g

Mas sof sodium bicarbonate = 1.018 g

Option B is the correct choice.

15) we will do all of these as these all these techniques cuts supply of oxygen, and fire will exthinguish.

So option d is the correct choice.

16) percent error =( (experimental value - accepted value) / accepted value) * 100

25 / 100 = ( 8.69 g mL-1 / accepted value) - 1

0.25 + 1 = 8.69 g mL-1 / accepted value

Accepted value = 6.95 g mL-1

So, option A is the correct choice.

17) all these methods are best for revision and sharpen the skills.

So, option D is the correct choice.