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This set of MCQs helps you brush up on important chemistry topics and prepare you to dive into skill practice.
How many moles of H3PO4 have the same number of hydrogen atoms as 1.5 moles of Ba(OH)2?
0.25 mol
1 mol
0.50 mol
1.50 mol
A 10 g sample of a pure compound composed of C, H, and O contains 4.0 g of C and 0.67 g of H. How many grams of O would be found in a 5.0-gram sample of the same substance?
1.34
1.6
2.66
4
A sample of nitrogen and oxygen compound is found by analysis to contain 7 g nitrogen and 16 g oxygen. What is its empirical formula?
NO
N2O4
NO4
NO2
How many moles of oxygen atoms are present in 6 x 10^24cules of ozone, O3?
30
18 x 10^24
10
6
Stilbene is an organic compound with the empirical formula C7H6 and a molar mass of 180.3 g/mol. How many hydrogen atoms would you expect to find in an 18 g sample of stilbene?
7.2 x 10^24
7.2 x 10^23
7.2 x 10^22
7.2 x 10^-23
If an iron-containing compound contains 5% iron (55 g/mol) by mass and there is one iron atom per formula unit, what is the best estimate of the molar mass of the compound?
550 g/mol
110 g/mol
1100 g/mol
2200 g/mol
When a solid change to a liquid it is called what?
Evaporating
Melting
Condensing
Freezing
True or false? Gases are hard to compress.
True
False
