PNCO 2023 School-Level Eliminations

In mammals, lactose (milk sugar) is metabolized to glucose (C₆H_I20₆), the key nutrient for generating chemical potential energy. How many grams of carbon are in 16.55 g of glucose?

• 6.62 g

• 9.93 g

• 4.14 g

• 12.41 g

Elemental analysis of a sample of an ionic compound showed 2.82 g of Na, 4.35 g of Ct, and 7.83 g of 0. What is the empirical formula and name of the compound? Atomic Masses: Na: 22.99 g/mol, Cl: 35.45 g/mol, O: 16.00 g/mol

• NaClO

• Na₂ClO₂

• NaClO₂

• NaClO₄

• Na₂ClO₄

Within the cylinders of a car's engine, the hydrocarbon octane (C₈H₁₈), one of many components of gasoline, mixes with oxygen from the air and burns to form carbon dioxide and water vapor. What are the coefficients (arranged in order of appearance) in the balanced equation for the complete combustion of octane?

_ C₈H₁₈ + _ O₂ → _ CO₂ + _H₂O

• 1, 12, 8, 9

• 1, 24, 8, 9

• 2, 25, 16, 18

• 2, 12, 8, 9

• 2, 24, 16, 18

Copper is obtained from sulfide ores, such as chalcocite, or Copper(I) Sulfide, by a multistep process. After an initial grinding, the first step is to "roast" the ore (heat it strongly with oxygen gas) to form powdered Copper(I) oxide and gaseous sulfur dioxide. How many grams of sulfur dioxide are formed when 10.0 mol of copper(I) sulfide is roasted? The molar mass of SO₂ is 64.04 g/mol.

• 320.4 g

• 640.7 g

• 1281 g

• 12.81 g

A fuel mixture used in the early days of rocketry is composed of two liquids, hydrazine (N₂H₄) and dinitrogen tetraoxide (N₂O₄), which ignite on contact to form nitrogen gas (N₂) and water vapor (H₂O). How many grams of nitrogen gas form when 100 g of N₂H₄ and 2.00 x 200 g of N₂O₄ are mixed?

• 65.6 g

• 182 g

• 131 g

• 91.6 g

How many hydrogen atoms are in 2.50 g of pharmacolite, CaHAsO₄•2H₂O (Molar Mass = 216.0)?

• 6.97 × 10²¹

• 2.09 × 10²²

• 2.79 × 10²²

• 3.48 × 10²²

A 2.50 L sample of butane gas (C₄H₁₀), measured at 22.0 ºC and 1.20 atm pressure, is combusted completely and the carbon dioxide gas collected at the same pressure and temperature. What volume of CO₂ is produced?

• 2.50 L

• 9.00 L

• 10.0 L

• 22.5 L

What volume of 18.0 M sulfuric acid must be diluted to 250.0 mL to afford a 0.55 M solution of sulfuric acid?

• 3.1 mL

• 4.5 mL

• 7.6 mL

• 31 mL

What is the concentration of H₂O₂ in a solution that is 30.0% by mass hydrogen peroxide and has a density of 1.11 g/mL?

• 9.79 M

• 12.6 M

• 18.5 M

• 32.6 M

Which ion gives a blue solution?

• Cu²⁺

• Zn²⁺

• Fe³⁺

• Ni²⁺

• Co²⁺