Chemical Reactions Quiz: MCQ Exam!
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What do you know about chemical reactions? A chemical reaction is a route that leads to the transformation of one group of chemical substances to another. Chemical reactions exemplify changes that only involve electrons' positions in the developing and breaking of chemical bonds among atoms, with no change to the nuclei. This quiz will give you a positive reaction of happiness when you pass with flying colors.
- 1.
Which one of the following represents a physical change?
- A.
Iron rusting
- B.
Paper burning
- C.
Water freezing
- D.
Dynamite exploding
Correct Answer
C. Water freezingExplanation
Water freezing is a physical change because it involves a change in the state of matter from a liquid to a solid. The molecules in water slow down and come closer together as the temperature decreases, forming a solid ice. The chemical composition of water remains the same during this process, making it a physical change rather than a chemical reaction.Rate this question:
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- 2.
.O {font-size:149%;} You can tell a chemical reaction because it always produces …
- A.
A different substance
- B.
Reactants
- C.
A change of state
- D.
Water
Correct Answer
A. A different substanceExplanation
A chemical reaction can be identified by the production of a different substance. This means that the reactants, which are the substances undergoing the reaction, combine and rearrange their atoms to form new substances with different chemical properties. This change in composition is a key characteristic of chemical reactions and distinguishes them from physical changes, such as changes in state or the formation of water.Rate this question:
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- 3.
Slide 5 To balance a chemical equation, you should change only the…
- A.
Subscripts
- B.
Coefficients
- C.
Chemical formulas
- D.
Location of the arrow
Correct Answer
B. CoefficientsExplanation
To balance a chemical equation, you should change only the coefficients. Coefficients are the numbers that are placed in front of the chemical formulas to balance the number of atoms on both sides of the equation. By adjusting the coefficients, you can ensure that the same number of atoms of each element is present on both sides of the equation, maintaining the law of conservation of mass. Changing the subscripts would alter the chemical formula, which would represent a different compound altogether. The location of the arrow represents the direction of the reaction and does not affect the balancing of the equation.Rate this question:
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- 4.
Slide 6 .O {font-size:149%;} If iron combines with oxygen to make iron oxide, the reactants are…
- A.
Iron oxide
- B.
Iron and iron oxide
- C.
Iron and oxygen
- D.
Oxygen and iron oxide
Correct Answer
C. Iron and oxygenExplanation
When iron combines with oxygen to form iron oxide, the reactants involved in the chemical reaction are iron and oxygen. Iron reacts with oxygen to produce iron oxide.Rate this question:
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- 5.
Slide 7 How many carbon atoms are there in C12H22O11?
- A.
6
- B.
12
- C.
18
- D.
45
Correct Answer
B. 12Explanation
The formula C12H22O11 represents a molecule of sucrose, which is a disaccharide made up of 12 carbon atoms. Therefore, the correct answer is 12.Rate this question:
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- 6.
Slide 8 How many oxygen atoms are in the product of this equation: 2H2 + O2 --> 2H2O
- A.
2
- B.
4
- C.
8
- D.
12
Correct Answer
A. 2Explanation
In the given equation, 2H2 + O2 -> 2H2O, the coefficient in front of O2 is 1. This means that there is only one molecule of O2 involved in the reaction. Since each molecule of O2 contains two oxygen atoms, the total number of oxygen atoms in the product (2H2O) is also 2.Rate this question:
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- 7.
Slide 9 .O {font-size:149%;} Which one of the following is a chemical equation?
- A.
Ice + heat --> water
- B.
Iron + oxygen --> rust
- C.
CO2
- D.
C + O2 --> CO2
Correct Answer
D. C + O2 --> CO2Explanation
The given answer, C + O2 --> CO2, is a chemical equation because it represents a chemical reaction between carbon (C) and oxygen (O2) to form carbon dioxide (CO2). In a chemical equation, the reactants are written on the left side of the arrow and the products are written on the right side. In this equation, C and O2 are the reactants, and CO2 is the product. The arrow indicates the direction of the reaction, showing the transformation of the reactants into the products.Rate this question:
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- 8.
.O {font-size:149%;} Balance the following equation: Ag + O2 --> Ag2O
- A.
Put a 2 in front of Ag
- B.
Add a subscript 2 to the end of Ag2O
- C.
Add a 4 in front of Ag and a 2 in front of Ag2O
- D.
Add a 2 in front of Ag and a 1 in front of Ag2O
Correct Answer
C. Add a 4 in front of Ag and a 2 in front of Ag2OExplanation
To balance the equation Ag + O2 --> Ag2O, you need to ensure that the number of each type of atom is the same on both sides of the equation. By adding a 4 in front of Ag and a 2 in front of Ag2O, you have balanced the equation. This is because now there are 4 atoms of Ag on both sides and 2 atoms of O on both sides, resulting in a balanced equation.Rate this question:
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- 9.
.O {font-size:149%;} In a chemical equation, the arrow means what?
- A.
A reaction is happening.
- B.
The two sides are equal.
- C.
The products flow into reactants.
- D.
The equation is balanced.
Correct Answer
A. A reaction is happening.Explanation
The arrow in a chemical equation indicates that a reaction is happening. It shows the direction in which the reactants are transforming into products. The arrow points from the reactants to the products, indicating the flow of the reaction.Rate this question:
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- 10.
.O {font-size:149%;} The reactants include 7 grams of C and 4 grams of O. What is the total amount of C and O in the products?
- A.
7 grams
- B.
4 grams
- C.
11 grams
- D.
None
Correct Answer
C. 11 gramsExplanation
The total amount of C and O in the products is 11 grams because the question states that the reactants include 7 grams of C and 4 grams of O. When these reactants undergo a chemical reaction, they will combine to form products. Since the reactants are completely consumed in the reaction, the total amount of C and O in the products will be equal to the sum of the amounts in the reactants, which is 7 grams + 4 grams = 11 grams. Therefore, the correct answer is 11 grams.Rate this question:
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- 11.
.O {font-size:149%;} Who first determined that the masses of the reactants and products must be the same?
- A.
Pasteur
- B.
Archimedes
- C.
Galileo
- D.
Lavoisier
Correct Answer
D. LavoisierExplanation
Lavoisier was the first to determine that the masses of the reactants and products must be the same. He conducted experiments on chemical reactions and observed that no mass was gained or lost during the process. This led him to propose the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. Lavoisier's work laid the foundation for modern chemistry and our understanding of the conservation of mass in chemical reactions.Rate this question:
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- 12.
.O {font-size:149%;} If you try to balance an equation by changing subscripts you change…
- A.
The number of molecules of product
- B.
The identity of the compound
- C.
The atomic number
- D.
The mass of the reactants
Correct Answer
B. The identity of the compoundExplanation
When balancing an equation by changing subscripts, you are altering the chemical formula of the compound. This means that you are changing the arrangement and type of atoms in the compound, thus changing its identity. The number of molecules of the product, the atomic number, and the mass of the reactants may be affected by balancing the equation, but the primary change is the identity of the compound itself.Rate this question:
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Mar 22, 2023Quiz Edited by
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Mar 12, 2009Quiz Created by
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