Multiple-choice Questions pick the correct answer

1. You know the mass of a sample of mercury, Hg and you want to determine how many mercury atoms are in the sample to do this you?

A. divide the mass by the molar mass and then divide by the Avogadro constant

B. divide the mass by the molar mass and then multiple the Avogadro constant

C. multiply the mass by the molar mass and then divide by the Avogadro constant

D. multiply the mass by the molar mass and then multiply by the Avogadro constant

E. divide the molar mass by mass and then multiply by the Avogadro constant

2. How many moles of argon (Ar) has 2.71 x 10²⁴ atoms

A. 16.3 mol

B. 1.63 mol

C. 4.50 mol

D. 27.1 mol

E. 0.222 mol

3. If 4 mol N₂(g) react with 9 mol H₂(g), how much N₂(g) will be left after the limiting reactant is completely consumed?

N₂(g) + 3H2(g) 2NH₃)(g)

A. 0 mol; N₂(g) is the limiting reactant

B. 1 mol

C. 2 mol

D. 3 mol

E. 5 mol

4. What Volume of a 2.0mol/L KBr(aq) solution would you need to add to a 500 mL volumetric flask, in order to make 500mL of a 0.10mol/L KBr(aq) solution?

A. 10mL

B. 20mL

C. 25mL

D. 40mL

E. 50mL

5. Consider the following chemical equation 2NaN₃(g) 2Na(s) + 3N₂(g) If 2 mol of sodium azide, NaN₃(g) react, what mass of sodium, Na(s) is produced?

A. 2g

B. 22.99g

C.45.98

D. 91.96g

E. 129.98g

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