Preliminary HSC Chemistry

Determine the missing coefficient for O₂ in the following chemical equation:

2C₄H₁₀ (g) + ___ O₂ (g) --> 8CO₂ (g) + 10H₂O (l)

• 5

• 8

• 13

• 16

A 12.2 g sample of X reacts with a sample of Y to form 78.9 of XY. What is the mass, in g, of Y that reacted?

• 12.2

• 66.7

• 78.9

• 91.1

Which of the following chemical equations is balanced correctly?

• 2H₂O (l) --> H₂ (g) + O₂ (g)

• Zn (s) + HCl (aq) --> ZnCl₂ (aq) + H₂ (g)

• Al₄C₃ (s) + 3H₂O (l) --> CH₄ (g) + 4Al(OH)₃ (aq)

• CH₄ (g) + 2O₂ (g) --> CO₂ (g) + 2H₂O (l)

A stone has a mass of 4.50 g and occupies a volume of 1.45 mL. What is the stone's density, in g/mL?

• 0.32

• 3.10

• 4.50

• 6.53

The mass, in g, of one molecule of carbon dioxide is closest to:

• 7.3 x 10^-23

• 44

• 6.022 X 10²³

• 44 x 6.022 x 10²³

A particular brand of plant fertilizer contains 58.5% urea (CO(NH₂)₂) as the only nitrogen-containing compound. The mass nitrogen, in g, in 125 g of this fertilizer is:

• 34.1

• 40.0

• 50.0

• 73.1

What is the volume, in L, occupied by a gas that has a mass of 3.20 kg and a density of 0.535 g/L?

• 5.98

• 1.71

• 1712

• 5980

The mass, in g, of calcium chloride that contains 6.022 x 10²³ chloride ions is:

• 35.45

• 55.49

• 74.53

• 110.98

Which sample contains the largest amount, in mol, of oxygen atoms?

• 0.20 mol NO₃

• 0.30 mol HCOOH

• 0.40 mol KMnO₄

• 0.70 mol H₂O₂

2.0 mol of Fe₂O₃ (s) reacts with excess CO (g) according to the following equation:

Fe₂O₃ (s) + 3CO (g) --> 2Fe (s) + 3CO₂ (g)

What mass of Fe (s), in g, is produced?

• 7.2 x 10^-2

• 4.0

• 1.1 x 10²

• 2.2 x 10²