Textbook Question
Which numbers are exact (and therefore have an unlimited number of significant figures)? a. π = 3.14 c. EPA gas mileage rating of 26 miles per gallon d. 1 gross = 144
2
views
Ch.1 - Matter, Measurement & Problem Solving
Tro5th EditionChemistry: A Molecular ApproachISBN: 9780134874371
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Matter, Measurement & Problem Solving117
- Ch.2 - Atoms & Elements106
- Ch.3 - Molecules and Compounds128
- Ch.4 - Chemical Reactions and Chemical Quantities56
- Ch.5 - Introduction to Solutions and Aqueous Solutions84
- Ch.6 - Gases112
- Ch.7 - Thermochemistry96
- Ch.8 - The Quantum-Mechanical Model of the Atom60
- Ch.9 - Periodic Properties of the Elements86
- Ch.10 - Chemical Bonding I: The Lewis Model91
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory85
- Ch.12 - Liquids, Solids & Intermolecular Forces51
- Ch.13 - Solids & Modern Materials48
- Ch.14 - Solutions93
- Ch.15 - Chemical Kinetics114
- Ch.16 - Chemical Equilibrium68
- Ch.17 - Acids and Bases137
- Ch.18 - Aqueous Ionic Equilibrium154
- Ch.19 - Free Energy & Thermodynamics91
- Ch.20 - Electrochemistry105
- Ch.21 - Radioactivity & Nuclear Chemistry74
- Ch.22 - Organic Chemistry141
Chapter 1, Problem 79b
Which numbers are exact (and therefore have an unlimited number of significant figures)? b. 12 in = 1 ft
Verified step by step guidance1
Identify the type of numbers involved in the conversion factor.
Recognize that conversion factors between units within the same measurement system (e.g., inches to feet) are defined values.
Understand that defined values are considered exact numbers.
Conclude that exact numbers have an unlimited number of significant figures.
Therefore, the numbers in the conversion factor '12 in = 1 ft' are exact.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Exact Numbers
Exact numbers are values that are counted or defined quantities, which have no uncertainty and therefore an infinite number of significant figures. Examples include the number of students in a classroom or defined conversion factors, such as 12 inches in a foot. Because they are not measured, they do not contribute to the uncertainty in calculations.
Recommended video:
Guided course
00:46
Number of Electrons in Shells
Significant Figures
Significant figures are the digits in a number that contribute to its precision, including all non-zero digits, any zeros between significant digits, and trailing zeros in the decimal portion. Understanding significant figures is crucial for accurately reporting measurements and results in scientific calculations, as they reflect the precision of the data.
Recommended video:
Guided course
01:09Significant Figures Example
Unit Conversion
Unit conversion involves changing a quantity expressed in one unit to another unit, often using conversion factors. In the example given, the relationship of 12 inches equaling 1 foot is a defined conversion factor, which is exact. This means that when performing calculations involving unit conversions, the exact nature of these factors ensures that the precision of the result is maintained.
Recommended video:
Guided course
01:56Conversion Factors
Related Practice
Textbook Question
Calculate to the correct number of significant figures. a. 89.3 × 77.0 × 0.08
3
views
Textbook Question
How many significant figures are in each number? c. 108,700 km
Textbook Question
How many significant figures are in each number? d. 1.563300×1011 m
1
views
1
rank
Textbook Question
Round each number to three significant figures. a. 79,845.82 b. 1.548937×107 c. 2.3499999995 d. 0.000045389
2
views
Textbook Question
Calculate to the correct number of significant figures. b. (5.01×105) / (7.8×102)
2
views