Test Flashcards
Out of the following which ones represent chemical changes:
Heating a wax block until the wax is liquid.
Mixing dye into liquid wax.
Dipping a wick into melted wax several times until the candle is the desired size.
Lighting the first candle to check that it burns evenly.
Number four
Out of the following which statement represents a physical change:
Water boils at 100°C.
Two substances react together then the temperature increases.
This kind of change does not change the nature of the substances.
The temperature rises and an ice cube melts
1,3,4
Hydrogen fuel, zero emission fuel, can be burnt with oxygen to power nonpolluting vehicles. Does the burning of hydrogen gas in this example demonstrate oxidation, synthesis, decomposition, or combustion?
Combustion
Why does water have a greater mass before but was then it does after it boils?
Water molecules are released into the air as gases
Which one of these is a chemical change? Your dog ripping up your homework, taking a glass of water and freezing it by placing it in the freezer, a plant collecting sunlight and turning it into food, filling up a balloon with hot air.
A plant collecting sunlight and turning it into food
Which of the following is a phenomenon that can be easily reversed? Burning wood, iron oxidizing to produce iron oxide, rusting of metals, condensation of water
Condensation of water
When silver metal comes into contact with sulfur, silver sulphide forms and the silver appears darker. This is an example of…
Synthesis
Which of the following choices contains only physical changes?
Mixing sugar and water, baking a cake, toasting bread.
Mixing sugar and water, mixing baking soda and water, boiling citric acid.
Boiling citric acid, baking a cake, toasting bread.
Mixing sugar and water, baking a cake, boiling citric acid.
Mixing sugar and water, mixing baking soda and water, acid.
Which of the following statements is false about a chemical change?
Molecules change before and after a chemical change.
They are generally reversible.
They change the nature and the characteristic properties of matter.
They do not follow the law of conservation of matter.
They do not follow the law of conservation of matter.
Which of the following statements is false about a physical change?
Molecules stay the same before and after a physical change.
One type of physical change is a phase change.
They are irreversible.
They do not change the nature or the characteristic properties of matter.
They are irreversible.
What is matter made up of
Atoms
Which of the following statements regarding Dalton’s atomic model is false? All matter is composed of Adams, all Adams of the same element identical, Adams of different elements are different, during a chemical reaction, Adams can I be separated from one another to form new substances.
During a chemical reaction, Adams gonna be separated from one another to form new substances
What is an element?
It’s a substance formed from one type of atoms
Which of the following is true? Two different elements can have the same chemical symbol. Two different elements can have exactly the same properties. Elements can combine together to form your sentences. It is possible to separate an element of the different kinds of atoms using chemical reactions.
Elements can combine together to form new substances
What are molecules made out of? One atem one type of atem multiple atems or multiple types of atem
Multiple atoms
