Year 11 Physics Question Paper

Your exam will be multiple choice Exam # 1 Introductory Chemistry Be sure to show your set up for all mathematical problems. Your answers must have the correct number of significant digits and the correct units. I. Chemistry is a quantitative science therefore we must make measurements. All measurements have an uncertainty that we need to be aware of in our calculations. A. We need to be able to determine the number of significant figures in a measurement. For the following measurement state the number of significant figures. (4pts) 1. 1.000 cm 2. 2.590 x 10-5 m 4 3. 0.020 g 4. 1000 cm 2 1

B. We need to be able to add, subtract, multiply, and divide with measurements. Solve the following problems. (4 pts) 1. 3.02 cm + 5 cm + 0.002 cm = 8
Chemists often deal with percent problems. As long as you remember that percent refers to per 100, these problems can be solved. 1. A penny minted after 1982 is composed of copper and zinc only. If a penny has a mass of 2.507 g and is 2.50 % copper. What is the mass of zinc in the coin? (5 pts) 2.507 g x 2.50/100 = 0.062675 g of Cu 2.507 g of penny - 0.062675 g of Cu = 2.444325 g = 2.444 g of Zn (2.44 g of Zn is correct also)

D. Density is a very important concept for chemist. The density of a substance can be obtained in a chemistry laboratory. 1. A rubber stopper with a mass of 23.75 g is dropped in a 50-mL graduated cylinder that has 20.4 mL of water. After the stopper is dropped in the graduated cylinder, the water level rises to 24.7 mL. What is the density of the rubber stopper? (5 pts) 2.375 g / (24.7 mL – 20.4 mL) = 5.523255814 g / mL = 5.52 g / mL (5.5 g /mL is
Give an example for each of the following terms: (8 pts) a. physical property – Appearance, melting point, boiling point, density, heat and electrical conductivity, solubility, and physical state under normal conditions are all examples of physical properties. b. chemical property – A chemical property of a substance describes its chemical reactions with other substances. The chemical property of sodium states that sodium will react with water to form hydrogen gas. c. physical change – A physical change include changing shape, volume, or physical state. For example when water changes to ice. d. chemical change - A chemical change always involves the formation of a new substance. Gas bubbles from the reaction of calcium with water. Fill in the blanks of the following table Symbol number of protons number of neutrons number of electrons mass number
37

Cl17 20 18

48

Cr3+ 24 24 21

24

Mg 12 12 12

37

48

24

Might not be on test. Ask teacher. Chlorine has two stable isotopes with masses of 34.97 amu and 36.97 amu. What is the relative abundance of the two isotopes? a. b. c. d. e. 50.00% 35Cl and 50.00 % 37Cl 35.45% 35Cl and 64.55 % 37Cl 64.55% 35Cl and 35.45% 37Cl 24.23% 35Cl and 75.77 % 37Cl 75.77 % 35Cl and 24.23 % 37Cl