File:No file chosen Whenever electrons of an atom unite with electrons of another atom, a chemical change occurs.

What is the cause?
What kind of change occurs?
Water expands when it freezes. Expanded ice floats on lakes and ponds.

What causes the water to expand?
What is the effect on the expanded ice?
Some metals will expand when heated. Expanded metals may bend.

What causes the metal to expand?
What are the effects of the expanded metal?
Gases expand when heated. An expanded gas occupies more space.

What causes the gas to expand?
What are the effects of the expanded gases?
Answer the above questions and give an example of a cause and effect relationship. See if you can think up a cause and effect relationship using acids, bases, and neutralization.

They all deal with hard evidence(scientific)

Stars are born within the clouds of dust and scattered throughout most galaxies. a familiar example of such as a dust cloud is the orion nebula. turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. as the cloud collapses, the material at the center begins to heat up. known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the milky way are paired or in groups of multiple stars.therefor, i would say the answer is: dust and gases contract.i hope this ! < 3