The particle theory of matter states that —

NaHCO3 is an example of —

Element is a

Which of the following is not a compound?

How many elements are represented in the compound?
Na₂CO₃

What cannot be broken down into other substances?

A combination of substances that are not chemically combined is called a(n)____________. 

This picture represents which of the following?

This picture represents which of the following?

This picture represents which of the following?

Two or more chemically combined atoms form —

Because zinc can combine with other substances but cannot be changed into a simpler substance by an ordinary chemical process, zinc is classified as —

Helium is a gas at room temperature. This is an example of a —

What is a chemical property that would be observed when a spark is introduced to a mixture of propane and oxygen?

An element has 1 electron in its valence shell. The element only has 4 shells. What is the element? 

Section 3 on the periodic table represents

Section 2 on the periodic table

Section 1 on the periodic table

Which scientist saw the atom as a positively charged sphere with negative particles  (electrons) embedded within?

Which scientist proposed a model of the atom in which the individual atoms where thought of as a large sphere in the middle with a positive charge and negatively charged electrons revolving around the center like the planets around the sun?

What does the nucleus of an atom contain?

The majority of an atom's mass exists where?

An experiment for a new asthma medication was set up into two groups. Group one was given the new drug for asthma, while group 2 was not given anything. The group not given anything serves as a 

When experimenting with the growth of a plant, a scientist uses three (of the same type of) plants, two different fertilizers, equal light, and equal water. The fact that we kept the light, plant, and water the same in each experiment are examples of ____________.

What is the dependent variable?

Jenny investigated how the height at which a ball is dropped affects how high the ball bounces. She used the same ball throughout the experiment. She kept the same surface to drop the ball on and the same way to release the ball. She dropped the ball from 100 cm, 200 cm, and 300 cm. She dropped the ball from each height 5 times. She measured how high the ball bounced back up for each trial and recorded it in her data table. She determined that the ball dropped from 300 cm had the highest return bounce.
What is the independent variable?

Jenny investigated how the height at which a ball is dropped affects how high the ball bounces. She used the same ball throughout the experiment. She kept the same surface to drop the ball on and the same way to release the ball. She dropped the ball from 100 cm, 200 cm, and 300 cm. She dropped the ball from each height 5 times. She measured how high the ball bounced back up for each trial and recorded it in her data table. She determined that the ball dropped from 300 cm had the highest return bounce.
What is the dependent variable?

Jenny investigated how the height at which a ball is dropped affects how high the ball bounces. She used the same ball throughout the experiment. She kept the same surface to drop the ball on and the same way to release the ball. She dropped the ball from 100 cm, 200 cm, and 300 cm. She dropped the ball from each height 5 times. She measured how high the ball bounced back up for each trial and recorded it in her data table. She determined that the ball dropped from 300 cm had the highest return bounce.
What is the constant?

Sydney  is testing the idea that plants grow faster when they are sung to. She plants five flowers in a pot (pot A) and five identical flowers in an identical pot (pot B). She sings to the flowers in pot A for one hour every day, but not to the flowers in pot B. At the end of his experiment, she finds that the flowers in pot A grew faster than those in pot B. This leads her to the conclusion that plants grow faster when they are sung to.    
Which of these is an alternative explanation for Sydney's results?