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Hw 1 solutions

Hw 1 solutions - Patel(ap29737 Homework 1 Sutclie(50985...

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Patel (ap29737) – Homework 1 – Sutcliffe – (50985) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. REMEMBER: DO NOT ROUND NU- MERICAL QUESTIONS. ENTER AT LEAST FOUR SIGNIFICANT FIGURES. 001 10.0 points Which of water, iron, ammonia, chromium, radon, and silicon are chemical compounds as opposed to elements? 1. radon and ammonia 2. chromium and water 3. iron and silicon 4. only water 5. water and ammonia correct Explanation: Water (H 2 O) and ammonia (NH 3 ) are com- posed of more than one element and are com- pounds. 002 10.0 points Which of the following describes a chemical change? 1. alcohol evaporates 2. wood is carved 3. gasoline burns in an engine correct 4. water is heated from 0 C to 50 C Explanation: A chemical change occurs when one or more substances are consumed (at least partially), and one or more new substances are formed. 003 10.0 points Convert 7 × 10 6 centigrams to kilograms. 1. 7 . 0 × 10 11 kg 2. 7 . 0 × 10 12 kg 3. 0.0070 kg 4. 7 . 0 × 10 15 kg 5. 70 kg correct 6. 7.0 kg 7. 700000 kg 8. 7 . 0 × 10 7 kg Explanation: 7 × 10 6 cg × 1 g 100 cg × kg 1000 g = 70 kg 004 10.0 points What is the volume of a sample of helium that has a mass of 4 . 61 × 10 3 g, and a density of 0 . 17847 g / L? Correct answer: 25 . 8307 mL. Explanation: m = 4 . 61 × 10 3 g d = 0 . 17847 g / L d = m V V = m d = 4 . 61 × 10 3 g 0 . 17847 g / L × 1000 mL L = 25 . 8307 mL 005 10.0 points Which isotope has 35 protons, 35 electrons, and 46 neutrons? 1. 81 46 Pd 2. 46 35 Br 3. 35 46 Pd 4. 81 35 Br correct Explanation: The standard nuclide symbol takes the form of A Z E were E is the element symbol, A is the mass number (number p + + number n ), and

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Patel (ap29737) – Homework 1 – Sutcliffe – (50985) 2 Z is the atomic number (number p + ). An isotope with 35 protons ( p + ) and 46 neutrons ( n ) has an atomic number of 35 and a mass number of 35 p + + 46 n = 81 amu. Br has an atomic number of 35, so the isotope is 81 35 Br.
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