Tough Chemistry Revision Quiz

1. How many carbon and oxygen atoms does a CO₂ molecule contain?

2 oxygen atoms and 2 carbon atoms

1 carbon atom and 1 oxygen atom

1 oxygen atom and 2 carbon atoms

2 oxygen atoms and 1 carbon atom

A CO2 molecule contains 2 oxygen atoms and 1 carbon atom.

Explanation

A CO2 molecule contains 2 oxygen atoms and 1 carbon atom.

2. Identify the type of reaction:

N₂ + H₂ -----> NH₃

Combination

Precipitation

Decomposition

Combustion

The given reaction involves the combination of nitrogen gas (N2) and hydrogen gas (H2) to form ammonia (NH3). This is a combination reaction because two or more substances are combining to form a single product.

Explanation

The given reaction involves the combination of nitrogen gas (N2) and hydrogen gas (H2) to form ammonia (NH3). This is a combination reaction because two or more substances are combining to form a single product.

3. Little Jonny is doing an experiment. He notices after mixing two chemicals that his new solution is bubbling. Little Jonny is like, 'Yo, what's going on here?!' - give little Jonny a tip to help him understand what is going on....

"Hey Jonny, bubbles are evidence of a precipitation reaction."

"Hey Jonny, your observation means that a gas is being produced."

"Hey Jonny, bubbles are evidence of a physical change."

Sorry, Johnny, no idea!

The correct answer explains to Little Jonny that the bubbling he observed indicates the production of gas. This suggests a chemical reaction is taking place between the two chemicals he mixed.

Explanation

The correct answer explains to Little Jonny that the bubbling he observed indicates the production of gas. This suggests a chemical reaction is taking place between the two chemicals he mixed.

4.

This is a diagram of which element?

O

Mg

Na

Ag

The diagram represents the element magnesium (Mg).

Explanation

The diagram represents the element magnesium (Mg).

5.

	Identify the type of reaction: H₂O ---> 2H₂ + O₂

Combination

Precipitation

Decomposition

Combustion

The given reaction involves breaking down a compound, H2O, into its constituent elements, 2H2 and O2. This process is known as decomposition, where a single compound is broken down into simpler substances.

Explanation

The given reaction involves breaking down a compound, H2O, into its constituent elements, 2H2 and O2. This process is known as decomposition, where a single compound is broken down into simpler substances.

6.

This is a diagram of which element?

C

He

Na

Au

The diagram represents the symbol for an element. Based on the options given, the correct answer is Na, which is the symbol for sodium on the periodic table.

Explanation

The diagram represents the symbol for an element. Based on the options given, the correct answer is Na, which is the symbol for sodium on the periodic table.

7. Little Jonny has permission from his teacher to test the gas product with a match. When he does this, a high pitch pop sound is heard with a flash of light! "wow," says Little Jonny. "What type of chemical reaction was that?!" Help Little Jonny out. Which statement is the MOST correct?

"Hey Jonny, that pop sound was the sound of compounds breaking down in a decomposition reaction."

"Hey Jonny, when you burn something, you see a release of energy in the form of light and heat. This should tell you that it is a combustion reaction."

"Hey, Jonny, when you burn something, you use the surrounding oxygen gas as a reactant which combines with your other reactant. A sudden release of energy in the form of light, sound, and heat (pop) is observed, and all of this is characteristic of a combustion reaction."

"Sorry, Jonny, no idea!"

The correct answer explains that when something is burned, oxygen gas from the surroundings reacts with the other reactant. This reaction results in a sudden release of energy in the form of light, sound, and heat, which is characteristic of a combustion reaction. This explanation aligns with the observation made by Little Jonny, where he heard a pop sound and saw a flash of light when testing the gas product with a match.

Explanation

The correct answer explains that when something is burned, oxygen gas from the surroundings reacts with the other reactant. This reaction results in a sudden release of energy in the form of light, sound, and heat, which is characteristic of a combustion reaction. This explanation aligns with the observation made by Little Jonny, where he heard a pop sound and saw a flash of light when testing the gas product with a match.

8.

	Identify the type of reaction: AgCl + BaBr₂ ----> AgBr + BaCl₂

Combination

Precipitation

Decomposition

Combustion

The given reaction involves the exchange of ions between AgCl and BaBr2, resulting in the formation of AgBr and BaCl2. This type of reaction is known as a precipitation reaction, as a solid precipitate (AgBr) is formed when two aqueous solutions are combined.

Explanation

The given reaction involves the exchange of ions between AgCl and BaBr2, resulting in the formation of AgBr and BaCl2. This type of reaction is known as a precipitation reaction, as a solid precipitate (AgBr) is formed when two aqueous solutions are combined.

9. Little Jonny is doing an experiment. He notices after mixing two liquids that his new solution is becoming cloudy. Little Jonny is like, 'Yo, what's going on here?!' - give little Jonny a tip to help him understand what is going on.

"Hey Jonny, I think your observation could be evidence of a combustion reaction."

"Hey Jonny, I think your observation could be evidence of a decomposition reaction."

"Hey Jonny, I think your observation could be evidence of a precipitation reaction."

Sorry, Johnny, no idea!

The correct answer is "Hey Jonny, I think your observation could be evidence of a precipitation reaction." When two liquids mix and the resulting solution becomes cloudy, it suggests that a precipitation reaction has occurred. In a precipitation reaction, two soluble substances react to form an insoluble product, which appears as a cloudy precipitate in the solution. This explanation aligns with Jonny's observation of the solution becoming cloudy after mixing the liquids.

Explanation

The correct answer is "Hey Jonny, I think your observation could be evidence of a precipitation reaction." When two liquids mix and the resulting solution becomes cloudy, it suggests that a precipitation reaction has occurred. In a precipitation reaction, two soluble substances react to form an insoluble product, which appears as a cloudy precipitate in the solution. This explanation aligns with Jonny's observation of the solution becoming cloudy after mixing the liquids.

10. Look carefully at this diagram of the atoms in some substances.

a = top row of 2 grey circles, bottom row of 2 grey circles, b = top of grey circle, red circle, grey circle and bottom row of grey circle, red circle, grey circle; c = top row of two grey circles, bottom row of two red circles; d = top row of a red circle, black circle, red circle and bottom row of a red circle, black circle, red circle; e = top row of two red circles, bottom row of two red circles; f = top row of red circle, black circle, red circle and bottom row of two grey circles

Which letter represents a mixture of elements?

A

B

C

D

E

F

In the given diagram, letter C represents a mixture of elements. This is because there are multiple different types of atoms represented by different colors in letter C, indicating that it is a combination of different elements.

Explanation

In the given diagram, letter C represents a mixture of elements. This is because there are multiple different types of atoms represented by different colors in letter C, indicating that it is a combination of different elements.