The distance from Earth to the Moon is approximately 240,000 mi. (c) The speed of light is 3.00 ⨉ 108 m/s. How long does it take for light to travel from Earth to the Moon and back again?
Ch.1 - Introduction: Matter, Energy, and Measurement

1장, 문제 78
Which of the following would you characterize as a pure or nearly pure substance?
a. baking powder
b. lemon juice
c. propane gas, used in outdoor gas grills
d. aluminum foil
e. ibuprofen
f. bourbon whiskey
g. helium gas
h. clear water pumped from a deep aquifer
검증된 단계별 안내1
Identify the definition of a pure substance: A pure substance consists of only one type of element or compound, with a uniform and definite composition.
Analyze each option to determine if it is a pure substance or a mixture: a. Baking powder is a mixture of several compounds, so it is not a pure substance.
b. Lemon juice is a mixture of water, citric acid, and other compounds, so it is not a pure substance.
c. Propane gas is a compound (C3H8) and can be considered a pure substance if it is not mixed with other gases.
d. Aluminum foil is made of aluminum (Al), an element, and is a pure substance.

비슷한 문제에 대한 검증된 영상 답변:
이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
4m주요 개념
질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.
Pure Substances
A pure substance consists of only one type of particle, which can be either an element or a compound. Pure substances have consistent properties and composition throughout, making them distinct from mixtures. For example, elements like helium or compounds like water are considered pure substances, while mixtures like baking powder or lemon juice contain multiple components.
추천 영상:
가이드 코스
Classification of Matter Example
Mixtures
Mixtures are combinations of two or more substances that retain their individual properties and can be separated by physical means. They can be homogeneous (uniform composition) or heterogeneous (distinct phases). For instance, baking powder and lemon juice are mixtures, as they contain various ingredients that do not chemically bond together.
추천 영상:
가이드 코스
Solubility and Mixtures
Chemical Composition
Chemical composition refers to the types and amounts of elements that make up a substance. Understanding the chemical composition helps in identifying whether a substance is pure or a mixture. For example, propane gas (C3H8) has a specific chemical formula indicating it is a pure compound, while substances like bourbon whiskey have complex compositions with various organic compounds.
추천 영상:
가이드 코스
Matter Composition
관련 실천
교과서 질문
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교과서 질문
The distance from Earth to the Moon is approximately 240,000 mi. (d) Earth travels around the Sun at an average speed of 29.783 km/s. Convert this speed to miles per hour.
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교과서 질문
The U.S. quarter has a mass of 5.67 g and is approximately 1.55 mm thick. (c) How much money would this stack contain?
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교과서 질문
The U.S. quarter has a mass of 5.67 g and is approximately 1.55 mm thick. (a) How many quarters would have to be stacked to reach 575 ft, the height of the Washington Monument?
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교과서 질문
The distance from Earth to the Moon is approximately 240,000 mi. (b) The peregrine falcon has been measured as traveling up to 350 km/ hr in a dive. If this falcon could fly to the Moon at this speed, how many seconds would it take?
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