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WorksheetsYear 8 - Reactions
Total questions: 28
Worksheet time: 34mins
What does the "thermal" in thermal decomposition mean?
sulfur
catalyst
heat
oven
What happens when CO2 is bubbled through limewater
It changes from pink to blue
It goes pop
It goes cloudy
It gets hot
Why does thermal decomposition need heat energy
to make magic
to break bonds
to make water
to work as a catalyst
Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?
Suppose a reaction were to happen in an open container in a lab. During the reaction, the scientist observes the chemicals bubble, and produce a gas. During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g. Explain what happened.
His chemical reaction defied the law of conservation of mass
The product destroyed mass during the reaction
The reactants created matter during the reaction
The gas that was produced was not able to be weighed since the container was open.
Which of the following statement is true about the breaking of bonds between molecules?
To break a bond between molecules, energy must be released by the molecule
To break a bond between molecules, no energy is needed.
To break a bond between molecules, energy must be absorbed by the molecule.
Which of the following is true about the formation of bonds between molecules?
Energy is given off when bonds are formed between molecules.
Energy is absorbed by the molecule when bonds are formed.
Energy is neither given off nor absorbed when bonds are formed.
The energy level of molecules will _________ during bond breaking and _________ during bond forming.
decrease, increase
increase, increase
increase, decrease
