Chemistry Chapter: The Chemical World

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Questions and Answers

Which of the following statements is a reasonable expression of Fleming's hypothesis?

Nutrient broth kills bacteria.

Mold kills bacteria.

Without mold in the culture dish, there were no clear areas in the bacteria.

There are clear areas around the *Penicillium* mold where *Staphylococcus* doesn't grow.

*Penicillium* mold produces a substance that kills *Staphylococcus*. (correct)

Fleming grew Penicillium in broth, then removed the Penicillium and poured the broth into culture dishes containing bacteria to see if the broth would kill the bacteria. What step in the scientific method does this represent?

Making a hypothesis

Rejecting the old hypothesis and making a new one

Collecting and organizing data

None of these

Testing a hypothesis by experiment (correct)

A scientific investigation is NOT valid unless every step in the scientific method is present and carried out in the exact order listed in this chapter.

False

Which of the following words is closest to the same meaning as hypothesis?

suggestion Signup and view all the answers

Why do scientists sometimes discard theories?

Contradictory observations are found Signup and view all the answers

Which of the following is a reasonable statement of Gary's hypothesis?

Plants that get more sunshine grow larger than plants that get less sunshine. Signup and view all the answers

What scientific reason might Gary have for insisting that the container size for the all plants be the same?

Gary wanted to make sure the size of the container did not affect differential plant growth in his experiment. Signup and view all the answers

What scientific reason might Gary have for insisting that all plants receive the same amount of water everyday?

Gary wanted to test the effect of shade on plant growth and therefore, he wanted to have no variables other than the amount of sunshine on the plants. Signup and view all the answers

What was the variable being tested in Gary's experiment?

the amount of sunshine Signup and view all the answers

Which of the following factors may be varying in Gary's experimental setup that he did not control?

All of the above are possible factors that Gary did not control. Signup and view all the answers

Why did the workers inject the monkey with typhus near the end of the experiment?

to prove that the monkey was not immune to typhus Signup and view all the answers

Which of the following is a reasonable statement of Eijkman's hypothesis?

The rice seed coat contains a nutrient that provides protection for chickens against polyneuritis. Signup and view all the answers

Which of the following statements is an interpretation, rather than an observation?

Animals which constantly stretch their necks will grow longer necks. Signup and view all the answers

Scientist A's hypothesis was that

animals which constantly stretch their necks will grow longer necks. Signup and view all the answers

Scientist A's hypothesis being discarded is

an example of the normal functioning of the scientific method. Signup and view all the answers

When a theory has been known for a long time, it becomes a law.

False Signup and view all the answers

In this experiment, what was the purpose of infecting cows C and D?

To serve as experimental controls (a comparison of treated to untreated cows). Signup and view all the answers

A hypothesis is

a tentative explanation for a phenomenon. Signup and view all the answers

Which statement best describes the reason for using experimental controls?

Experimental controls allow comparison between groups that are different in only one independent variable. Signup and view all the answers

A student decides to set up an experiment to determine the relationship between the growth rate of plants and the presence of detergent in the soil. He sets up 10 seed pots. In five of the seed pots, he mixes a precise amount of detergent with the soil and the other five seed pots have no detergent in the soil. The five seed pots with detergent are placed in the sun and the five seed pots with no detergent are placed in the shade. All 10 seed pots receive the same amount of water and the same number and type of seeds. He grows the plants for two months and charts the growth every two days. What is wrong with his experiment?

The student has two independent variables. Signup and view all the answers

A scientist plants two rows of corn for experimentation. She puts fertilizer on row 1 but does not put fertilizer on row 2. Both rows receive the same amount of sun and water. She checks the growth of the corn over the course of five months. What is acting as the control in this experiment?

Corn without fertilizer. Signup and view all the answers

If you have a control group for your experiment, which of the following is true?

The control group must be identical to the test group except for one variable. Signup and view all the answers

If the hypothesis is rejected by the experiment, then:

the experiment may have been a success. Signup and view all the answers

A well-substantiated explanation of an aspect of the natural world is a:

theory Signup and view all the answers

Study Notes

Chapter Overview

The Chemical World is a chapter on Chemistry
It covers topics like Sand and Water, Chemicals Compose Ordinary Things, The Scientific Method, Analyzing and Interpreting Data, A Beginning Chemist, Hypothesis, Theories, & Laws and the Scope of Chemistry
There are exercises at the end of each chapter
Information is shared under a CK-12 license and authored by Marisa Alviar-Agnew & Henry Agnew.

1.1 Sand and Water

Sand and water are shared under a not declared license
This section is authored, remixed, and/or curated by LibreTexts
Further details were on page 396607 in LibreTexts

1.2 Chemicals Compose Ordinary Things

Chemistry is the study of matter's structure, composition, properties and reactive characteristics.
Matter is anything that has mass and occupies space.
Chemistry involves the transformation of matter, like crude oil into petroleum products or metal ores into metals.
Matter is made up of atoms composed of neutrons, protons, and electrons.
Atoms are incredibly small; a copper penny contains 28 sextillion atoms (28,000,000,000,000,000,000,000).
The nucleus, at the center of the atom, is very small, very dense, positively charged, and contains most of the atom's mass.
Electrons orbit the nucleus in a diffuse cloud, with a net negative charge and same number as positive charges.

1.3 The Scientific Method - How Chemists Think

The scientific method involves observations, formulating hypotheses, experiments, and drawing conclusions.
Observations can be qualitative (describing properties without numbers) or quantitative (measurements).
A hypothesis is a tentative explanation for an observation or set of observations.
An experiment tests a hypothesis in a controlled way.
Conclusions are drawn from experiment results, either supporting or modifying the hypothesis.

1.4 Analyzing and Interpreting Data

This section details analyzing and interpreting data, but lacks the specific details you requested.

1.5 A Beginning Chemist - How to Succeed

Chemists apply the scientific method to investigate matter and its transformations
Knowledge of chemical properties and elements
The application of chemistry to solve problems in various fields (engineering, archeology, paleontology etc)

1.6 Hypothesis, Theories, and Laws

A fact is an established observation or experiment.
A hypothesis is an educated guess or a tentative explanation.
A theory is a comprehensive explanation supported by facts & experiments.
A theory is not a guess, but a well-substantiated explanation of a phenomenon in the natural world.
A scientific law summarizes patterns in observations.

1.7 The Scope of Chemistry

Chemistry studies matter's composition, properties, and changes.
Chemistry is a central science that connects with various disciplines like physics, biology, geology etc.
Main branches of chemistry include physical, organic, inorganic, analytical, and biochemistry.

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Explore the fundamentals of chemistry in this quiz based on 'The Chemical World' chapter. Covering key topics such as the composition of ordinary things, the scientific method, and the basics of matter, this quiz will test your understanding of essential chemical concepts. Perfect for beginner chemists looking to solidify their knowledge.