Chemical or molecular formulas? Symbols from the periodic table are used to show which atoms are present in a molecule and subscripts show the number of atoms and of each type in the molecule.
The answer is the first option. Gas burning in an engine is an example of a chemical change. Chemical change is a change where the substance changes in identity or form new substances after undergoing a process. In this case, the gas reacts with oxygen forming combustion products, commonly carbon dioxide and water.
Answer:
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The independent variable is the one that is changed by the scientist. To insure a fair test, a good experiment has only ONE independent variable. As the scientist changes the independent variable, he or she records the data that they collect.
C. A new substance is produced. All others are physical changes.
Answer:
Semiconductors are poor conductors at low temperatures, but their resistance decreases with increasing temperature.
Explanation:
A semiconductor can be defined as a crystalline solid substance that has its conductivity lying between that of a metal and an insulator, due to the effects of temperature or an addition of an impurity. Semiconductors are classified into two main categories;
1. Extrinsic semiconductor.
2. Intrinsic semiconductor.
The statement which best describes the electrical conductivity of metals and semiconductors is that semiconductors are poor conductors at low temperatures, but their resistance decreases with increasing temperature.
This ultimately implies that, semiconductors are typically an insulator (poor conductor) at low temperatures and a good conductor at high temperatures.
Additionally, conduction involves the transfer of electric charge or thermal energy due to the movement of particles. When the conduction relates to electric charge, it is known as electrical conduction while when it relates to thermal energy, it is known as heat conduction.
