1
Which of the following elements has 3 isotopes?
A Hydrogen
B Helium
C Lithium
D Beryllium
A
2
Which particle is the heaviest?
A Beta
B Gamma
C Alpha
D Hydrogen
C
3
Different isotopes of the same element contain different numbers of:
A electrons.
B neutrons.
C protons.
D nuclei.
B
4
A radioisotope has a half-life of 1000 years. What percentage of the original amount would be left after 2000 years?
25% (after 2 half-lives)
5
What makes the nuclei of some atoms unstable?
The neutrons and protons are not held together as strongly as in other atoms.
6
The graph below shows the radioactive decay of iodine-131.
(a) What is the half-life of iodine-131?
(b) How many radioactive particles would be left after 40 days?
(a) 8 days
(b) 50
7
Which of the following is a physical change?
A Letting off fireworks
B Making a cup of tea
C Adding Mentos to diet coke
D Boiling water to make steam
D
8
The substances you end with in a chemical reaction are most accurately called:
A reactants.
B chemicals.
C products.
D compounds.
C
9
Students measure 2.0 g of baking soda and 5.0 g of vinegar. They mix them together in a beaker and watch as bubbles form. The mass of the liquid product is 6.7 g.
Based on the Law of Conservation of Mass, what should the mass of the products be?
A 5.0 g
B 6.7 g
C 7.0 g
D 10.0 g
C
10
Acidic and basic compounds occur naturally in foods. Individually, they give distinctive tastes to the foods in which they occur. These tastes are, respectively,:
A sour and bitter.
B bitter and sour.
C sweet and sour.
D bitter and sweet.
A
11
The name given to a reaction in which an acid and a base are mixed to produce water and a salt is:
A cancellation.
B destruction.
C neutralisation.
D elimination.
C
12
Which of the following contributes to acid rain?
A Oxygen
B Hydrogen gas
C Steam
D Pollution
D
13
When fossil fuels are burnt to provide energy in a combustion reaction, one product is always:
A hydrogen
B water
C oxygen.
D methane
B
14
Which of the following is not a fossil fuel?
A Petrol
B Coal
C Uranium
D Wood
C
15
Describe:
(a) an example of a chemical change
(b) an example of a physical change.
Examples:
(a) Wood burning
(b) Ice melting
16
(a) State the Law of Conservation of Mass.
(b) State the Law of Constant Proportions, and give an example.
(a) In a chemical reaction, the total mass of reactants equals the total mass of products.
(b) No matter where they are found or how they are formed, a compound always has the same relative numbers of each of its elements (e.g. carbon dioxide is always CO2 and sodium chloride is always NaCl).
17
For the following reaction, state all the:
(a) products
(b) reactants.
potassium iodide + lead nitrate à potassium nitrate + lead iodide
(a) Potassium nitrate, lead iodide
(b) Potassium iodide, lead nitrate
18
When potassium nitrate dissolves in water, the temperature decreases. Is this an example of an exothermic or endothermic process?
Endothermic
19
Dynamite is one of the most well known chemicals used in the explosives industry.
Is the use of dynamite in demolishing a building an example of an endothermic or exothermic process? How do you know?
Exothermic process. Energy is transferred to the surroundings.
20
Give two common examples of:
(a) acids
(b) bases.
(a) Hydrochloric, citric
(b) Sodium hydroxide, ammonia
21
Fill in the gaps to write a chemical word equation that describes the process of aerobic respiration.
Glucose + _ → _ + water
In order: oxygen, carbon dioxide
22
A sample of acid rain turned universal indicator yellow.
(a) What would you expect its pH to be?
(b) Is it a strong or a weak acid?
(a) pH 5-6
(b) Weak acid
23
Two students added some sodium hydroxide drop by drop to some hydrochloric acid in a test tube and used a pH meter to follow what happened to the pH of their solution. Their results are shown in the graph below.
(a) Explain why the pH of the solution kept going up.
(b) Write a word equation for this reaction.
(c) At how many drops was the acid neutralised?Justify your answer.
(d) If the students allowed the water to evaporate after the neutralisation reaction, what would be left in the test tube?
(a) Sodium hydroxide is a base, which caused the pH to increase and become more basic.
(b) sodium hydroxide + hydrochloric acid à sodium chloride + water
(c) 25 drops. The pH at this point is 7, which is neutral.
(d) A salt (NaCl)
5