Chemistry and Engineering: Introduction - Lecture 1 Practice Questions PDF

Lecture 1 practice questions Chemistry and Engineering: Introduction 1) According to the law of Conservation of Mass, how would you describe the total mass before a chemical reaction? A) It is greater than the total mass after the chemical reaction B) It is equal to the tot...

Lecture 1 practice questions Chemistry and Engineering: Introduction 1) According to the law of Conservation of Mass, how would you describe the total mass before a chemical reaction? A) It is greater than the total mass after the chemical reaction B) It is equal to the total mass after the chemical reaction C) It can vary D) It is less than the total mass after the chemical reaction 2) In a reaction between 100 g of element X and an unknown mass of element Y, 150 g of product XY was formed (according to the following equation) X + Y  XY , what was the mass of element Y used in the reaction? A) 25 g B) 75 g C) 50 g D) 100 g 3) In a chemical reaction, 50 g of substance Sodium (Na) reacts with 30 g of substance Chlorine (Cl) to form compound Sodium Chloride (NaCl). After the reaction, it was found that 15 g of Sodium (Na) remained unreacted. If the equation of the reaction is Na + Cl  NaCl, what is the mass of compound NaCl formed? A) 50 g B) 95 g C) 80 g D) 65 g 4) In a sample of a pure compound, if the mass ratio of elements A and B is 3:2, which of the following statements can be inferred? A) The ratio will change in different samples of the same substance B) The ratio of A to B will always be 3:2 in any pure sample of the same compound C) The ratio is only valid for one specific sample D) The mass ratio can vary based on the method of extraction or preparation 1 5) A sample of a certain compound contains the elements Magnesium (Mg) and Bromine (Br) and has a total mass of 75 g. If the mass of Magnesium (Mg) in the compound is 27 g. what mass of Bromine (Br) would be present in a 200 g sample of the same compound? A) 48 g B) 173 g C) 128 g D) 205 g 6) Two pure samples of the Potassium Iodide (KI) are analyzed. Sample 1 has 28 g of Potassium (K) and 72 g of Iodine (I). Sample 2 contains 40 g of Potassium (K). According to the Law of Definite Proportions, what mass of Iodine (I) would be in Sample 2? A) 100.2 g B) 90.5 g C) 72 g D) 102.9 g 7) A compound consisting of Phosphorus (P) and Chlorine (Cl) is found in a mass ratio of 5:12 in Sample 1, which was prepared in a chemistry lab. Now, Sample 2, which contains the same pure compound, was prepared in a research facility and has a total mass of 120 g. What mass of chlorine (Cl) would be present in Sample 2? A) 84.7 g B) 96 g C) 120.5 g D) 144.2 g 8) The Law of Multiple Proportions states that: A) Elements combine in fixed mass ratios B) The total mass before and after a chemical reaction remains the same C) The mass ratios of one element combining with a fixed mass of another element are simple whole numbers D) Elements always combine in 1:1 mass ratios 2 9) In a study, it was found that one sample of a compound composed of sulfur and oxygen where it contains 32 g of sulfur and 48 g of oxygen. A second sample of the same elements contains 32 g of sulfur and 96 g of oxygen. What is the ratio of the masses of oxygen in the two compounds, and what conclusion can be drawn about the Law of Multiple Proportions? A) 1:2; confirms the law B) 1:1; does not confirm the law C) 1:3; confirms the law D) 1:2; does not confirm the law 10) A student in a chemistry lab prepared two different compounds containing only nitrogen and oxygen. She calculated the mass of each element in each of the compounds. Compound Mass of Nitrogen (g) Mass of Oxygen (g) 1 2.5 2.5 2 3.2 1.6 According to the given information, do these compounds follow the law of multiple proportions? A) Yes B) No C) Not enough information 11) Which law is supported by the following statement? In hydrogen peroxide there are 16 grams of oxygen per 1 g of hydrogen and in water there are 8 grams of oxygen per 1 g of hydrogen. A) Law of conservation of mass B) Law of definite proportions C) Law of multiple proportions D) Law of multiple definites 3 12) The element carbon has an atomic number of 6 and a mass number of 12. What is the correct number of protons, neutrons, and electrons in a neutral carbon atom? A) 6 protons, 6 neutrons, 6 electrons B) 12 protons, 6 neutrons, 6 electrons C) 6 protons, 12 neutrons, 6 electrons D) 12 protons, 6 neutrons, 12 electrons 13) An element in the periodic table has an atomic number of 17 and a mass number of 35. Which of the following correctly identifies this element, its symbol, and the number of neutrons in its atom (use the periodic table)? A) Chlorine (Cl), 18 neutrons B) Argon (Ar), 18 neutrons C) Chlorine (Cl), 17 neutrons D) Sulfur (S), 18 neutrons 14) Which group of elements in the periodic table is known as the noble gases? A) Group 1 B) Group 2 C) Group 17 D) Group 18 15) An element is found in Group 2 of the periodic table and has a mass number of 24. It contains 12 neutrons in its nucleus. Which of the following correctly describes the atomic number, element symbol, and number of protons for this element (use the periodic table)? A) Atomic number: 24, Symbol: Mg, Protons: 12 B) Atomic number: 12, Symbol: Mg, Protons: 12 C) Atomic number: 12, Symbol: Ca, Protons: 24 D) Atomic number: 24, Symbol: Ca, Protons: 12 4 16) Which of the following is a transition metal (use the periodic table)? A) Fe B) He C) Li D) A&B 17) An isotope of magnesium, 24Mg, has an atomic number of 12. If another isotope of magnesium, 26Mg, is considered, how many neutrons does this isotope have? And what is the correct symbol for this isotope, including the atomic number? A) 14 neutrons; 26 14Mg B) 12 neutrons; 26 14Mg C) 12 neutrons; 26 12Mg D) 14 neutrons; 26 12Mg 18) An element, sulfur (S), has the following isotopes: 32  S with an atomic mass of 31.972 amu. 34  S with an atomic mass of 33.967 amu. If a sample’s average mass number is 32.47 amu, what would be the relative abundance of 32S? A) 50% B) 25% C) 75% D) 100% 19) Consider the element Potassium (K), which has an atomic number of 19 and a mass number of 39. When potassium loses one electron to form a potassium ion, what are the respective numbers of protons, neutrons, and electrons in the ion, and what is its overall charge? A) 19 protons, 20 neutrons, 19 electrons; Charge: +1 B) 19 protons, 20 neutrons, 18 electrons; Charge: +1 C) 19 protons, 18 neutrons, 19 electrons; Charge: 0 D) 19 protons, 20 neutrons, 18 electrons; Charge: -1 5 20) Which of the following options correctly classifies the given substances into atoms, diatomic molecules, polyatomic molecules, and ions? A) He (Atom); O2 (Diatomic molecule); H2O (Polyatomic molecule); Na+ (Ion) B) Ne (Diatomic molecule); N2 (Atom); CH4 (Ion); Cl− (Polyatomic molecule) C) Ar (Ion); F2 (Atom); C3H8 (Diatomic molecule); Ca2+ (Polyatomic molecule) D) Xe (Atom); S8 (Diatomic molecule); C2H6 (Ion); Mg2+ (Polyatomic molecule) 21) Which of the following is an alkali metal, a transition metal and a metalloid, respectively (use the periodic table)? A) Na, K, I B) Ca, Mn, As C) Li, Mg, Se D) Cs, Mn, Si Model Answers: 1) B 2) C 3) D 4) B 5) C 6) D 7) A 8) C 9) A 10) A 11) C 12) A 13) A 14) D 15) B 16) A 17) D 18) C 19) B 20) A 21) D 6