SCIN 131 Quiz 4

Question 5 of 32 3.0/ 3.0 Points `I was wading in the creek and discovered what I thought to be a small meteorite. I took a small sample of it home, ran some fancy schmancy chemical tests on it, and determined it was 18.0% chromium by mass. How many grams of this meteorite would I need to be able to have 15.0 g of chromium?  A. 100  B. 120.0  C. 2.7  D. 83.3 Feedback: Great! Mass percent discussed in Chapter 6.2. Question 6 of 32 3.0/ 3.0 Points Since 1983, pennies have been made with zinc and plated with copper. Prior to 1983, pennies were about 95% copper and 5% tin and zinc. However, from , pennies were pure copper. If you had a penny from 1800 that had a mass of 2.78g, how many atoms of copperwould you have?  A. 8.13 × 10-26  B. 1.67 x 1024  C. 2.63 × 1022  D. 1.19 × 1026  E.6.02 × 1023 Feedback: Great! Mass percent discussed in Chapter 6.2. Question 7 of 32 3.0/ 3.0 Points In the research lab, I have finally done it! I've discovered a new compound! I have determined that its empirical formula, but in order to determine its actual molecular formula, I need to know which of the following?  A. the number of moles of the compound in a 1.00 g sample of the substance  B. the density of the compound  C. the boiling point and freezing point of the compound  D. the molar mass of the compound.  E. none of these Feedback: Great! Empirical Formula discussed in Chapter 6.2.