CHEM FINAL REVIEW

Which of the following correctly expresses 52,030.2 m in scientific notation?

• 5.203 × 104 m

• 5.20302 × 105 m

• 
  5.20 × 104 m

• 
  5.20302 × 104 m

The distance between carbon atoms in ethylene is 134 picometers. Which of the following expresses that distance in meters?

• 1.34 × 10^–10 m

• 1.34 × 10^–7 m

• 1.34 × 10^–13 m

• 1.34 × 10^–12 m

The ripening of fruit, once picked, is an example of physical change.

• True

• False

The chemical symbol for potassium is

• Po.

• 
  P.

• Pt.

• K.

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH)₂.

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na₂SO₄. 

• 2.409 × 10²⁴ O atoms

• 1.244 × 10²³ O atoms

• 4.976 × 10²³ O atoms

• 
  2.915 × 10²⁴ O atoms

The mass of a sample is 550 milligrams. Which of the following expresses that mass in kilograms?

• 
  5.5 × 10^–6 kg

• 5.5 × 10⁵ kg

• 
  5.5 × 10^–4 kg

• 
  5.5 × 10⁸ kg

The symbol for the SI base unit of mass is

• kg.

• 
  lb

• 
  g.

• 
  mg.

Aluminum reacts with oxygen to produce aluminum oxide which can be used as an adsorbent, desiccant, or catalyst for organic reactions.

    4Al(s) + 3O₂(g) → 2Al₂O₃(s)

A mixture of 82.49 g of aluminum (M = 26.98 g/mol) and 117.65 g of oxygen (M = 32.00 g/mol) is allowed to react. Identify the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete.

• Oxygen is the limiting reactant; 35.16 g of aluminum remain.

• Aluminum is the limiting reactant; 44.24 g of oxygen remain.

• Aluminum is the limiting reactant; 16.70 g of oxygen remain.

• Oxygen is the limiting reactant; 19.81 g of aluminum remain.

Select the answer that expresses the result of this calculation with the correct number of significant figures.

• 13

• 
  13.3568

• 
  13.36

• 13.357