Moles and Mass

How many moles of lead in 42g of Na (M=23)?

• 42/23
• 23/42
• 42 x 6 x 10²³

What is the mass of 1.2 x 10²⁴  atoms of S (M =32)?

• 1.2 x.10²⁴ x 32
• 1.2 x 10²⁴ / 6 x 10²³
• 2 x 32

How many atoms of Cl in  35.5g of Cl₂ molecules (M(Cl) = 35.5)

• 35.5/35.5 x 6 x 10²³
• 71 x 6 x 10²³
• 71/35.5 x 6 x 10²³

How many moles of  CO molecules in 56g of CO (M(C) = 12, M(O) =16 ?

• 2
• 28/56
• 56 x 6 x 10²³

How many moles of H in 32g of methane (CH₄).  M(CH₄) = 16

• 32/16
• 32 x 16
• 32 /16 x 4
• 32/16  x 4

What is the mass of O in 100g of CaCO₃ (M (CaCO₃ = 100)

• 1
• 100/48
• 100/16
• 3

What is the mass of 1.2 x 10²⁵ atoms of sulfur (M(S) =32) ?

• 1.2.x.10²⁵ / 6 x 10²³ x 32
• 1.2 x 10²⁵ x 32
• 2 x 32

How many atoms of H in 4.5g of H₂O?  M(H₂O) =18 ?

• 4.5 / 18
• 18/4.5 x 6 x 10²³
• 0.25 x 6 x 10²³

In 53g of Na₂CO₃ (M(Na₂CO₃) = 106,  M(O) =16), what is the mass of O?

• 53 /106
• 53/106 x 16
• 53 /106 x 3 x 16

How many molecules of of methane are there if there are 24 x 10²³ atoms of H? (MCH₄ = 16)

• 4
• 1
• 24 x 10²³ / 16