Atoms and Molecules Numerical problems

What is the number of moles in 32 grams of oxygen (O2)?

• 1 mole

• 4 moles

• 0.5 moles

• 2 moles

Calculate the empirical formula for a compound with 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.

• C3H6O

• CH3O2

• CH2O

• C2H4O2

If an atom has 12 protons and 14 neutrons, what is the number of neutrons?

• 16

• 14

• 10

• 14 protons

• 12

Define atomic mass unit (amu) and its significance in chemistry.

• An atomic mass unit (amu) is one twelfth of the mass of a carbon-12 atom.

• An atomic mass unit (amu) is a unit used to measure temperature in chemistry.

• An atomic mass unit (amu) is equal to the mass of a hydrogen atom.

• An atomic mass unit (amu) is defined as the mass of a neutron.

How many molecules are in 2 moles of water (H2O)?

• 1.2044 x 10^24

• 3.6888 x 10^24

• 6.022 x 10^23

• 1.008 x 10^24

What is the molecular formula for a compound with an empirical formula of CH2 and a molar mass of 28 g/mol?

• C2H2

• C3H6

• CH4

• C2H4

If a sample contains 3.01 x 10^23 atoms of carbon, how many moles does it represent?

• 0.250 moles

• 0.500 moles

• 2.00 moles

• 1.00 moles

Determine the number of neutrons in an isotope of chlorine with a mass number of 35.

• 18

• 22

• 16

• 20

What is Avogadro's number and why is it important in chemistry?

• Avogadro's number is the mass of a mole in grams.

• Avogadro's number is 6.022 x 10^23.

• Avogadro's number is 3.14159.

• Avogadro's number is used to calculate the density of gases.

Calculate the molecular weight of glucose (C6H12O6).

• 165.45 g/mol

• 180.18 g/mol

• 200.25 g/mol

• 150.12 g/mol