Gen Chem 1 Review

What is the atomic number of an element?

• The atomic number of an element is a decimal number represented by the letter A.

• The atomic number of an element is a whole number that is unique to each element and is represented by the letter Z.

• The atomic number of an element is the same for all elements.

• The atomic number of an element is determined by the number of neutrons in the nucleus.

How many protons are present in a carbon atom?

• 8

• 4

• 10

• 6

Calculate the number of moles in 25 grams of water (H2O).

• 2.5 moles

• 0.25 moles

• 3.14 moles

• 1.387 moles

What is the molar mass of carbon dioxide (CO2)?

• 28.01 g/mol

• 44.01 g/mol

• 50.00 g/mol

• 36.02 g/mol

How many significant figures are in the number 0.00345?

• 4

• 2

• 5

• 3

Perform the following dimensional analysis: 5.6 g to mg.

• 5600 mg

• 560 mg

• 56 mg

• 5.6 mg

What is the mass of 3 moles of oxygen atoms (O)?

• 32 grams

• 48 grams

• 64 grams

• 16 grams

How many atoms are present in 2 moles of carbon (C)?

• Approximately 1.2044 x 10^24 atoms

• Approximately 6.022 x 10^23 atoms

• Approximately 3.2044 x 10^24 atoms

• Approximately 5.2044 x 10^24 atoms

Perform the following stoichiometry calculation: How many grams of water (H2O) are produced from the reaction of 4 moles of hydrogen gas (H2) and excess oxygen gas (O2)?

• 72.08 grams

• 36.04 grams

• 18.02 grams

• 144.16 grams

Round off the following number to 3 significant figures: 0.00876.

• 0.00875

• 0.00878

• 0.00880

• 0.00870