Year 8 Reaction revision

Year 8 Reaction revision

Rearranging atoms

Balancing equations

Combustion

Thermal decomposition

Exothermic and endothermic 

Energy level diagrams

Bond energies.

What is the process of rearranging atoms in a substance called?

1. Molecular transformation
2. Chemical reaction
3. Atomic shuffling
4. Elemental reorganization

What is the term for the rearrangement of atoms within molecules?

1. Elemental modification
2. Molecular reorganization
3. Chemical rearrangement
4. Atomic shifting

What is the result of rearranging atoms in a chemical reaction?

1. Formation of new compounds
2. Molecule separation
3. Elemental fusion
4. Atom fusion

What is the term for breaking and reforming chemical bonds to rearrange atoms?

1. Elemental combination
2. Molecular synthesis
3. Chemical transformation
4. Atomic disassembly

What does not change during a chemical reaction

1. The products made
2. The total number of products
3. The total number of atoms each element
4. The total number of reactants.

What is the principle stating that matter cannot be created or destroyed?

1. Law of Motion
2. Principle of Displacement
3. Law of Conservation of Mass
4. Theory of Relativity

According to the law of conservation of mass, what happens to the total mass of a closed system?

1. It decreases
2. It increases
3. It fluctuates
4. It remains constant

What is the fundamental idea behind the law of conservation of mass?

1. Matter can transform into energy
2. Matter can defy gravity
3. Matter cannot vanish or come into being
4. Matter can change color

In a chemical reaction, what does the conservation of mass imply about the total mass of the reactants and products?

1. It doubles
2. It remains the same
3. It quadruples
4. It halves

What is a balanced symbol equation?

1. An equation without any numbers or symbols.
2. An equation with only one element represented.
3. An equation with unequal numbers of atoms on each side.
4. An equation where the number of atoms of each element is equal on both sides.

Why is it important to balance a symbol equation?

1. To confuse people who read the equation.
2. To make the equation look neat and tidy.
3. To satisfy the law of conservation of mass.
4. To increase the chemical reactivity of the substances.

What does the coefficient in a balanced symbol equation represent?

1. The volume of the substance.
2. The state of matter of a substance.
3. The atomic number of an element.
4. The number of molecules or atoms of a substance.

How can you balance a symbol equation?

1. By adding more reactants to one side of the equation.
2. By ignoring the need for balance.
3. By changing the chemical formula of the substances.
4. By adjusting the coefficients of the reactants and products.

What is the general equation for a combustion reaction?

1. 2H2 + O2 → 2H2O
2. C + O2 → CO2
3. CH4 + 2O2 → CO2 + 2H2O
4. H2O → H2 + O2

Which of the following is not a product of a complete combustion reaction?

1. Water vapor
2. Sulfur dioxide
3. Carbon monoxide
4. Carbon dioxide

What is the primary requirement for a substance to undergo a combustion reaction?

1. High pressure
2. Absence of light
3. Presence of oxygen
4. Low temperature

Which type of reaction is a combustion reaction?

1. Decomposition
2. Exothermic
3. Synthesis
4. Endothermic

What is the role of a catalyst in a combustion reaction?

1. Speeds up the reaction
2. Forms new products
3. Increases the oxygen concentration
4. Reduces the temperature

What is thermal decomposition?

1. A process in which a substance combines with heat.
2. A process in which a substance breaks down due to heat.
3. A process in which a substance changes color due to heat.
4. A process in which a substance evaporates due to heat.

Which of the following is an example of thermal decomposition?

1. Formation of water from hydrogen and oxygen.
2. Decomposition of limestone to form quicklime and carbon dioxide.
3. Formation of rust on iron due to exposure to air.
4. Formation of salt from the reaction of an acid and a base.

What role does heat play in thermal decomposition?

1. Heat increases the stability of the compound.
2. Heat slows down the decomposition reaction.
3. Heat changes the chemical composition of the compound.
4. Heat provides the activation energy for the decomposition reaction.

Why is thermal decomposition important in industrial processes?

1. It increases the shelf life of perishable goods.
2. It allows the production of useful substances from raw materials.
3. It helps in the purification of water.
4. It reduces the environmental impact of manufacturing.

Which type of reaction absorbs heat from the surroundings?

1. Endergonic
2. Endothermic
3. Thermodynamic
4. Exothermic

In which type of reaction is heat released to the surroundings?

1. Exergonic
2. Endothermic
3. Thermodynamic
4. Exothermic

Which term describes a reaction that feels cold to the touch?

1. Exergonic
2. Exothermic
3. Endothermic
4. Endotherm

What type of reaction is photosynthesis considered to be?

1. Endergonic
2. Exothermic
3. Thermodynamic
4. Endothermic

In which type of reaction does the temperature of the surroundings increase?

1. Exergonic
2. Endothermic
3. Thermodynamic
4. Exothermic

What does an energy level diagram represent?

1. Distribution of energy levels for electrons
2. Atomic mass of an element
3. Number of electrons in an atom
4. Speed of light in a vacuum

What is the significance of the spacing between energy levels in a diagram?

1. Represents the number of protons in an atom
2. Shows the atomic radius of an element
3. Reflects the ionization energy of an element
4. Indicates the energy gap between levels

How does an electron transition from a lower to a higher energy level?

1. Releases energy as light
2. Undergoes nuclear fusion
3. Changes its spin orientation
4. Absorbs a specific amount of energy

What do downward arrows in an energy level diagram indicate?

1. Increase in atomic mass
2. Formation of a new element
3. Conversion of matter into energy
4. Electron transitioning to a lower energy level

What does the term 'ground state' refer to in an energy level diagram?

1. Highest energy level occupied by an electron
2. Lowest energy level occupied by an electron
3. Total energy of an atom
4. Energy released during nuclear decay

What is bond energy?

1. The energy required to break a chemical bond
2. The energy of an ionic bond
3. The energy stored in a chemical bond
4. The energy released when a bond forms

Which factor affects bond energy?

1. The volume of the molecule
2. The type of bond and the atoms involved
3. The temperature of the surroundings
4. The color of the compound

What is the typical unit for bond energy?

1. Kilojoules per mole (kJ/mol)
2. Grams per liter (g/L)
3. Kelvin (K)
4. Meters per second (m/s)

How does bond length relate to bond energy?

1. Longer bond length, higher bond energy
2. Bond length has no effect on bond energy
3. Shorter bond length, higher bond energy
4. Bond energy is unrelated to bond length

What happens to bond energy in an exothermic reaction?

1. Bond energy is absorbed
2. Bond energy becomes unpredictable
3. Bond energy remains unchanged
4. Bond energy is released