8.1  Multiple Choice Questions 1) A physical change A) occurs when iron rusts. B) occurs when sugar is heated into caramel. C) occurs when glucose is converted into energy within your cells. D) occurs when water is evaporated. E) occurs when propane is burned for heat. 2) A chemical change A) occurs when methane gas is burned. B) occurs when paper is shredded. C) occurs when water is vaporized. D) occurs when salt is dissolved in water. E) occurs when powdered lemonade is stirred into water. 3) Which of the following represents a physical property? A) Sodium metal is extremely reactive with chlorine gas. B) Mercury is a silvery liquid at room temperature. C) Aluminum has a tendency to “rust.” D) Butane is highly flammable. E) Argon has an unreactive nature. 4) Which of the following represents a chemical property of hydrogen gas? A) It is gaseous at room temperature. B) It is less dense than air. C) It reacts explosively with oxygen. D) It is colorless. E) It is tasteless. 5) Global warming is thought to be caused by the increase of one particular gas. Name the gas. A) oxygen B) carbon monoxide C) carbon dioxide D) nitrogen E) helium 6) How many grams of Li3N can be formed from 1.75 moles of Li? Assume an excess of nitrogen. 6 Li(s) + N2(g) → 2 Li3N(s) A) 18.3 g Li3N B) 20.3 g Li3N C) 58.3 g Li3N D) 61.0 g Li3N E) 15.1 g Li3N 7) How many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the following reaction? The molar mass of KNO3 is 101.11 g/mol. 4 KNO3(s) → 2 K2O(s) + 2 N2(g) + 5 O2(g) A) 0.290 mol O2 B) 0.580 mol O2 C) 18.5 mol O2 D) 0.724 mol O2 E) 1.73 mol O2 8) How many moles of nitrogen are formed when 58.6 g of KNO3 decomposes according to the following reaction? The molar mass of KNO3 is 101.11 g/mol. 4 KNO3(s) → 2 K2O(s) + 2 N2(g) + 5 O2(g) A) 0.290 mol N2 B) 0.580 mol N2 C) 18.5 mol N2 D) 0.724 mol N2 E) 1.73 mol N2 9) Two samples of calcium fluoride are decomposed into their constituent elements. The first sample produced 0.154 g of calcium and 0.146 g of fluorine. If the second sample produced 294 mg of fluorine, how many g of calcium were formed? A) 0.280 g B) 3.09 × 102 g C) 3.13 g D) 0.309 g E) 2.80 × 102 g 10) Two samples of potassium iodide are decomposed into their constituent elements. The first sample produced 13.0 g of potassium and 42.3 g of iodine. If the second sample produced 24.4 kg of potassium, how many kg of iodine were produced? A) 13.3 kg B) 22.5 kg C) 79.4 kg D) 44.4 kg E) 92.4 kg 1