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Questions and Answers
In an experiment, the variable that is not changed is referred to as the:
In an experiment, the variable that is not changed is referred to as the:
- Dependent variable
- Measurement variable
- Independent variable
- Controlled variable (correct)
When solutions of lithium fluoride (LiF) and lead chloride (PbCl2) are mixed, solid lead fluoride (PbF2) forms. Which ions remain dissolved in the solution?
When solutions of lithium fluoride (LiF) and lead chloride (PbCl2) are mixed, solid lead fluoride (PbF2) forms. Which ions remain dissolved in the solution?
- Pb2+ and F-
- Li+ and Cl-
- Pb2+ and Cl-
- Li+ and F- (correct)
The rate of a chemical reaction will increase if:
The rate of a chemical reaction will increase if:
- A catalyst is used (correct)
- The temperature decreases
- The surface area of the reactants decreases
- The concentration of the reactants decreases
Which of the following is not a balanced equation?
Which of the following is not a balanced equation?
Which of the following is a covalent compound?
Which of the following is a covalent compound?
Which of the following ions does not have a charge of ‘-2’?
Which of the following ions does not have a charge of ‘-2’?
In the periodic table, elements are placed in the same group because they have the same:
In the periodic table, elements are placed in the same group because they have the same:
The mass number of an element always indicates the number of:
The mass number of an element always indicates the number of:
In terms of collision theory, a chemical reaction only occurs when:
In terms of collision theory, a chemical reaction only occurs when:
In an energy level (profile) diagram, activation energy is a measure of:
In an energy level (profile) diagram, activation energy is a measure of:
The use of fertilisers in farming which leads to waste entering the waterways such as rivers would be classified as what type of pollutant?
The use of fertilisers in farming which leads to waste entering the waterways such as rivers would be classified as what type of pollutant?
When an acid was added to a solid, a reaction occurred that produced a clear solution and a colorless gas. The gas popped when a lighted match was placed in the mouth of the test-tube. The gas must have been:
When an acid was added to a solid, a reaction occurred that produced a clear solution and a colorless gas. The gas popped when a lighted match was placed in the mouth of the test-tube. The gas must have been:
Name a possible formula for an ionic compound formed by the elements V, W, X, Y, and Z with their respective charges. Include subscripts as necessary.
Name a possible formula for an ionic compound formed by the elements V, W, X, Y, and Z with their respective charges. Include subscripts as necessary.
Which of the following observations would be a quantitative observation?
Which of the following observations would be a quantitative observation?
Which of the following is the correct naming for the following groups?
Which of the following is the correct naming for the following groups?
Write the letter corresponding to the element in the Periodic Table for each given criteria.
Write the letter corresponding to the element in the Periodic Table for each given criteria.
Complete the table by providing the formula of the ionic compound formed by Fe3+ and SCN- ions.
Complete the table by providing the formula of the ionic compound formed by Fe3+ and SCN- ions.
Study Notes
Semester 1 Exam 2023: Year 10 Science - Chemistry
Multiple Choice Section
- In an experiment, the controlled variable is the one that remains unchanged.
- When solutions of lithium fluoride (LiF) and lead chloride (PbCl2) are mixed, solid lead fluoride (PbF2) forms, and Li+ and Cl- ions remain dissolved in the solution.
- The rate of a chemical reaction will increase if a catalyst is used.
- A covalent compound is H2O.
- Chromate ions have a charge of -2.
- In the periodic table, elements are placed in the same group because they have the same number of valence (outermost) electrons.
- The mass number of an element indicates the number of protons + neutrons.
- A chemical reaction only occurs when reactants collide in the correct orientation with sufficient energy.
- Activation energy is a measure of the energy required for successful collisions to occur.
- Fertilisers in farming can be classified as chemical pollutants.
- When an acid is added to a solid, a reaction occurs, producing a clear solution and a colourless gas, which is likely to be carbon dioxide.
Short Answer Section
Question 1: Periodic Table
- An alkali earth metal in period 4 is an element with symbol B.
- An element with an electron configuration of 2.8.3 is H.
- An element in period 3 with 5 electrons in the outermost shell is K.
- An element with a full outer shell of electrons is L.
- An element that would form an ion with a charge of -1 is M.
- A metal with one valence electron is C.
Question 2: Ionic Compounds
- The formula of an ionic compound FeI3 has ions Fe³⁺ and I⁻.
Question 3: Investigation of Aluminium Reaction
- The balanced formula equation for the reaction is Al (s) + H2SO4 (aq) → Al2(SO4)3 (aq) + H2 (g).
- Independent variable: concentration of acid.
- Dependent variable: time taken for Aluminium to react completely.
- Hypothesis: As the concentration of acid increases, the time taken for Aluminium to react completely decreases.
- Safety precaution: Wear protective gloves and goggles.
- Observations that confirm a chemical reaction has taken place: the beaker feels warm, and a colourless gas is produced.
- According to collision theory, as the concentration of acid increases, the frequency of successful collisions increases, resulting in a shorter time for Aluminium to react completely.
Question 4: Calcium
- Element Calcium-40: atomic number 20, atomic mass 40, electron configuration 2.8.8.2.
Question 5: Zinc and Hydrogen Gas
- Zinc metal: metallic bonding, does not conduct electricity, malleable, has a high melting point.
- Hydrogen gas: molecular bonding, does not conduct electricity, not malleable, has a low boiling point.
Question 6: Ionic Bonding
- In a solid, ionic bonding is present, and the substance does not conduct electricity.
- In a dissolved state, the ions are free to move, and the substance conducts electricity.
Question 7: Reaction of Potassium Carbonate and Barium Nitrate
- The type of reaction is a precipitation reaction.
- Word equation: Potassium carbonate + Barium nitrate → Potassium nitrate + Barium carbonate.
- Balanced chemical equation: K2CO3 (aq) + Ba(NO3)2 (aq) → 2KNO3 (aq) + BaCO3 (s).
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