Chem 106 Exam 1 Fall 2024 PDF

North Carolina A & T State University Exam 1 CHEM 106-014 Fall 2024 Instructor: Dr. Richard Yeboah Abrokwah Last Name________________________________ First Name___________________________________ 1*. Write the version of your exam under the Period Section of the Scantr...

North Carolina A & T State University Exam 1 CHEM 106-014 Fall 2024 Instructor: Dr. Richard Yeboah Abrokwah Last Name________________________________ First Name___________________________________ 1*. Write the version of your exam under the Period Section of the Scantron. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Dr. King measured the length of her new porch to be 76.445m. The degree of uncertainty of her porch is _____________ A) 0.445 B) ± 0.445 C) ± 0.005 D) ± 0.001 E) ± 76 2) which of the following balances has the least Accuracy? (A) analytical balance, ± 0.0001 g (b) electronic balance, ± 0.001 g (c) beam balance, ± 0.01 g (d) platform balance, ± 0.1 g e) All balances have the same uncertainty. 3) Identify the characteristics of a liquid. A) definite volume and definite shape B) definite volume and no definite shape C) no definite shape and definite volume D) no definite shape and no definite volume 4) Identify the description of an atom. A) neutrons and electrons in nucleus; protons in orbitals B) neutrons in nucleus; protons and electrons in orbitals C) protons and neutrons in nucleus; electrons in orbitals D) protons and electrons in nucleus; neutrons in orbitals E) electrons in nucleus; protons and neutrons in orbitals 5) Molecules can be described as A) mixtures of two or more pure substances. B) mixtures of two or more elements that has a specific ratio between components. C) two or more atoms chemically joined together. D) heterogeneous mixtures. E) homogeneous mixtures. 6) The isotope that contains 27 protons, 33 neutrons, and 27 electrons is A. arsenic-60. B. neodymium-60. C. cobalt-33. D. cobalt-60. E. cobalt-27. 7) All of the following will lead to a homogeneous mixture EXCEPT A) sugar and coffee. B) mud and water. C) salt and water. D) ice tea and lemonade. E) vinegar and water. 8) Which of the following is NOT an intensive property A) Density. B) melting point C) Mass D) Color E) Boiling point 9) The correct answer (reported to the proper number of significant figures) to the following is 6.3 × 3.25 = ________ A) 20.45 B) 20.475 C) 20.5 D) 20.48 E) 20 10) How many of the following numbers contain 3 significant figures? 0. 509 1.050 0.0 500 1.06 × 1024 A) one B) two C) three D) four 11) The correct answer (reported to the proper number of significant figures) to the following is 5.2143 + 0.633 + 12.91 = A) 18.7573 B) 18.8 C) 18.76 D) 18.757 E) 18.75 (12) If a car has an EPA mileage rating of 30 miles per gallon, what is this rating in kilometers per liter? (3.785 L = 1gal, and 1mile= 1.609km ) A) 200 km/L B) 180 km/L C) 70 km/L D) 12.75 km/L E) 4.93km/L [°F = 1.8 (°C) + 32 ] [ °C + 273 = K ] For questions 13 and 14 13) The highest temperature ever recorded in Phoenix, Arizona, was 122F. Express this temperature in C. A) 50.0C B) 64.4C C) 67.8C D) 162.0C E) 219.6C 14) A temperature of 300. K is the same as __________°F. A) 711 B) 260 C) 351 D) 81 E) 63 Conversion Factors for questions 15 and 16 1 mol atoms = 6.022 × 10 23 atoms 1 mol = molar mass (g) 1 mol = 6.022 × 10 23 molecule 15) What mass (in g) does 7.98 moles of Krypton (Kr-atomic number 36) have? A) 668 g B) 952 g C) 422 g D) 480 g E) 288 g 16) How many atoms of oxygen are in 2.50 moles of SO2? A) 4.52 × 1024 atoms B) 1.51 × 1024 atoms C) 5.02 × 1023 atoms D) 7.53 × 1023 atoms E) 3.01 × 1024 atoms 17) When waves of equal amplitude from two sources are out of phase interact, it is called A) destructive interference. B) diffraction. C) constructive interference. D) effusion. E) amplitude.  %Y1 %Y2 Average atomicmassY = (atomic mass Y1 ) + (atomic mass Y2 ) 100 100 18) Calculate the atomic mass of gallium if gallium has 2 naturally occurring isotopes with the following masses and natural abundances. Isotope Mass (amu) Relative abundance Ga-69 68.9256 amu 60.11% Ga-71 70.9247 amu 39.89% a. 70.00 amu b. 69.93 amu c. 70.68 amu d. 69.72 amu e. 69.80 amu 19) Dr. Vassel needs to pour 80 g of chloroform. If the density of the chloroform is 1.48 g/mL, what volume of chloroform the student needs to pour? Round your answer to 3 significant digits. D=mass/volume a. 118.4 mL b. 54.054 mL c. 0.0185 mL d. 54.1 mL 20) When a wave encounters an obstacle or a slit that is comparable in size to its wavelength, it bends around it. This characteristic is called A) destructive interference. B) diffraction. C) constructive interference. D) effusion. E) amplitude. 21)Wave (a) has the a. shorter wavelength and lower frequency than wave (b). b. shorter wavelength and higher frequency than wave (b). c. longer wavelength and higher frequency than wave (b). d. longer wavelength and lower frequency than wave (b). 22. The fireworks we observed on Independence Day is caused by A. Ionization of electrons in an atom to produce light of different energy B. Natural brightness of different elements C. Burning of metals to produce light D. Excitation of electrons of atoms to higher energy levels followed by emission of light photons of different energy. E. None of the above 23) Electromagnetic radiation with a wavelength ( ) of 640 nm appears as orange light to the human eye. The frequency (v) of this light is ________. ( 1nm = 1.0 x 10-9m) A) 4.688 × B) 4.688 × C) 1.920 × D) 1.920 × E) 2.133 × c = 3.0 x 10 8m/s 24) The visible light we see and electrons can behave as (a) Both a wave and particle (B) only a wave (c) only a particle (d) Neither a wave nor particle (e) none of the above 25) Determine the mass of a particle with a De Broglie wavelength of 3.45 × 10-34 m and a velocity of 6.55 m/s 2 2 h = 6.626 x 10-34J 1 J = 1 kg · m /s ). A) 293kg B) 2.93 x 10-9 kg C) 1.81 × 10-10kg D) 0.293kg E) 2.76 × 109kg 26) Determine the energy change (energy emitted) with an electronic transition from n =3 to n =2 in the hydrogen atom. A) +3.03 × 1019 J B) -1.82 × 10-19 J C) -5.51 × 10-19 J D) -3.03 × 10-19 J E) +2.69 × 10-19 J 27) Ultraviolet light (Source) of total energy 3.83 × 10–3 J strikes a metal surface and emits a of light (photon) at a wavelength of 3.37 × 10–7 m. How many photons does this correspond to? hc Esource = Ephotons x Number of photons E=  A) 4.688 x 1012photons B) 10 photons C) 50 photons D) 125 photons E) 6.49 × 1015 photons 28) The scientist who proved that we cannot determine the position and speed of microscopic objects (e.g. electrons) at the same time was A) Niels Bohr B) Albert Einstein C) De Broglie D) Werner Heisenberg E) Max Planck Exam1 Extra Credit 20Points 1. Dr. Belizaire and Dr. Vassell had 3 solids S1,S2, S3 and 2 liquids L1 L2. They placed them in a graduated cylinder that contained water. After shaking them for a minute, they let them sit in the cylinder for about 5mins. They saw that the mixture separated as shown below. (a) If the density of water (blue color) is 1g/ml, use the principle of density to assign possible density values in g/ml to the solids and liquids. 8Points = = 1g/ml= = = = (b) Explain/justify the reason behind your answer 2Points 2. Use the concept of Atomic Notation to complete the table 10 Points Atomic Number of protons Number of Number of Net Charge Notation in Nucleus neutrons in electrons Nucleus 53 26 Fe2+ 26 33 3+ 85 125 86 13 14 10