Chapter 2: Measurement and Calculations

In an experiment, onion plants of different ages were exposed to various amounts of caffeine to determine the effect of caffeine on cell growth. Temperature, amount of water, and light were kept constant. Which of these statements about the experiment is definitely true?

• the results may not be valid because there were two variables

• the amount of caffeine used was a control

• temperature, water, and light were the only variables

• onion plants can be used to model the effects of caffeine on living things

Which of these is the variable in an experiment designed to determine whether steel rusts more quickly near a lake or in a desert in one year?

• amount of rust

• time of exposure

• amount of water in the air

• mass of the steel

Which of these recorded observations is qualitative, rather than quantitative?

• a chemical reaction is complete in 2.3 s

• the solid has a mass of 23.4 g

• the compound melts at 87.5° C

• iron is denser than aluminum

Which of these terms best describes the following statement?

"A solution of the unknown compound turned litmisu paper blue."

• hypothesis

• model

• quantitative observation

• qualitative observation

Which of these statements is true of the scientific method?

• the steps may vary somewhat to suti the experiment

• working scientists rarely use it

• scientists must follow its steps exactly

• scientists rarely publish the results of experiments

Theories are considered successful only if they

• can be used to make accurate predictions

• can be stated in simple terms

• can be written in the form of an equation

• have been accepted by all scientists

Which of the following is not a stage of the scientific method?

• using a hypothesis to sell a new product

• observing, collecting, and communicating data

• formulating theories

• formulating hypotheses

An experiment is designed to measure the effect of global temperature increase on ocean levels. In this experiment, if the ocean level is compared to the average ocean level over the last 100 years, then the average ocean level over the last 100 years would be considered

• a model

• a variable

• the hypothesis

• the control

The unit cm³ is used to express

• length

• mass

• volume

• time

The SI base units for time and temperature are

• hour and degree Celsius

• second and degree Celsius

• hour and Kelvin

• second and Kelvin