General Chemistry 1 Practice Exam 1

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Questions and Answers

How many tungsten atoms are contained in a jewelry piece with a diameter of 12.3mm?

2.08 x 1027 atoms

4.92 x 1023 atoms (correct)

6.14 x 1022 atoms

1.66 x 1028 atoms

What is the density of acetone in g/cm3?

7.91 x 10-4 g/cm3

7.91 x 10-1 g/cm3 (correct)

7.91 x 107 g/cm3

7.91 x 103 g/cm3

Which species does NOT have the same number of neutrons as 31P3-?

35K+ (correct)

31P

34Ar

29Si

What is the correct number of significant figures for the result of 114.mL – 7.× 101 mL?

44.mL Signup and view all the answers

How is the ordering of energy levels for GS, ES-A, and ES-B arranged from lowest energy to highest energy?

GS < ES-A < ES-B Signup and view all the answers

Which statement about a pure nickel sphere and a pure silver sphere with identical volumes is true?

They have the same total number of protons Signup and view all the answers

What is the volume of a sphere with a diameter of 12.3 mm?

5.66 cm³ Signup and view all the answers

Which molecule transitions first from ground state to excited electronic state before emitting light at 510 nm?

GS Signup and view all the answers

What changes when 12C is replaced by 13C in a molecule?

The total number of neutrons in the molecule Signup and view all the answers

Which electronic transition in a hydrogen atom emits a photon with sufficient frequency to activate a specific molecular switch?

n = 4 to n = 2 Signup and view all the answers

What is the mass of a mole of electrons in g/mol?

5.49 × 10-4 g/mol Signup and view all the answers

Which quantity is NOT dependent on the wavelength of a photon of light?

The intensity Signup and view all the answers

Which element could have an atom mass of 5.148 x 10-23 g?

He Signup and view all the answers

Which sample consists of the greatest number of atoms?

1.5 g graphite Signup and view all the answers

How should the average atomic mass of magnesium be estimated from its isotopes' abundances?

(79  24 amu + 10  25 amu + 11  26 amu) / 100 Signup and view all the answers

What is the mass of water lost from the sample after drying, reported with the correct number of significant figures?

4.61 g Signup and view all the answers

In what way does the stability of an electron in the n = 1 state of a hydrogen atom differ from when it is in the n = 2 state?

The n = 1 electron is more stable because it has a lower energy than in n = 2. Signup and view all the answers

What does the value 10.81 on the periodic table for Boron represent?

An average Boron atom weighs 10.81 amu; a mole of average Boron atoms weighs 10.81 g. Signup and view all the answers

When converting the first ionization energy of Scandium from J/atom to kJ/mol, what is the correct conversion result?

6.32 x 102 kJ/mol Signup and view all the answers

What scientific principle is demonstrated by diffraction patterns emerging from a beam of electrons passing through two slits?

The wave-like behavior of matter Signup and view all the answers

Which statement about the addition of Zinc as a micronutrient in commercially produced foods is accurate?

Zinc is required for proper immune function and growth. Signup and view all the answers

How does the energy of an electron in a hydrogen atom change with an increase in principal quantum number (n)?

The energy increases as n increases. Signup and view all the answers

What is the significance of the value 10.81 listed for Boron in the periodic table?

It is the atomic mass of Boron, averaged over all its isotopes. Signup and view all the answers

What is the recommended daily value of zinc, in mg?

44 mg Signup and view all the answers

If the volume of a cell is approximately $1.0 imes 10^3 , ext{μm}^3$, what is the typical volume of the cell nucleus assuming it is about 10% of the total cell volume?

10 μm³ Signup and view all the answers

What is the density of DNA in g/cm³?

1.7 g/cm³ Signup and view all the answers

Why does the number density of Titanium (Ti) remain lower than that of Beryllium (Be) despite Ti having a higher density?

Ti has a larger atomic volume. Signup and view all the answers

What is the mass of DNA inside a typical cell nucleus in grams?

6.5 × 10^-9 g Signup and view all the answers

What is the wavelength of the photon emitted during the electronic transition in the hydrogen atom?

1.282 μm Signup and view all the answers

If the number density of Silicon (Si) is to be calculated as atoms per cm³, which of the following must be known?

Density, atomic mass, and volume. Signup and view all the answers

If an electronic transition in hydrogen moves from n = 5 to a lower state, what factor could determine the new quantum state?

The wavelength of the emitted photon. Signup and view all the answers

Study Notes

Practice Exam 1 Overview

The exam tests various fundamental concepts in General Chemistry.
Key topics include density conversions, atomic structure, molecular transitions, and isotopes.

Density and Conversions

Acetone density: 791 kg/m³ converts to 0.791 g/cm³.
Tungsten density: 19.25 g/cm³; volume formula V = (4/3)πr³ helps find the number of atoms in a jewelry piece.
Loss of water mass during drying reviewed: Initial and final masses reported affect significant figure calculations.

Atomic Structure and Isotopes

Isotopes display different neutron counts compared to standard elements: 31P³⁻ compared with other elements like K⁺ and Si.
Isotopic labeling used in molecular studies; substitution of 13C for 12C changes neutron count but retains proton and electron totals.

Electronic Transitions and Energy States

Green Fluorescent Protein (GFP) absorbs light at 395 nm, transitioning from ground state (GS) to excited states (ES-A, ES-B). Energy hierarchy: GS < ES-A < ES-B.
Hydrogen atom transitions include various energy states; transitions n = 2 to n = 1 are significant for high-frequency photon emissions.

Calculations and Formula Applications

Conversion of electron mass (9.11 x 10^-31 kg) to molar mass yields 5.49 x 10^-4 g/mol.
Average atomic mass calculations for elements consider percent natural abundances, applied to Magnesium's isotopes.

Significant Figures and Empirical Measurements

Performing calculations with significant figures is crucial, especially in volume and mass differences.
Specific density and mass allow comparison of atomic number densities among elements like Be, Si, and Ti.

Micronutrient Content

Zinc daily value calculated from cereal content illustrates the importance of nutrient labeling.

Work-Out Problems

Density and volume calculations for nucleic DNA provide practical applications of density formulas and significant figures.
Electronic transitions in hydrogen can be used to infer higher frequency transitions through wavelength calculations.

General Observations

Understanding fundamental principles of chemistry is essential for solving practical problems.
Mastery of significant figures, density, isotopes, and atomic structure is critical for exam preparation.

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Description

Test your knowledge with this practice exam for General Chemistry 1. Covering key concepts and calculations, this quiz includes questions on density, atomic counts, and more. Be sure to use appropriate resources as you attempt this timed assessment.