# Yakal 4th Quarter Exam In Science 10

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• 1.

### Which of the following scientists studied the relationship between the volume and temperature of    gas at constant pressure?

• A.

Robert Boyle

• B.

Jacques Charles

• C.

• D.

Gay - Lussac

B. Jacques Charles
Explanation
Jacques Charles studied the relationship between the volume and temperature of gas at constant pressure. This relationship is known as Charles's Law, which states that the volume of a gas is directly proportional to its temperature when the pressure is held constant. Charles conducted experiments in the late 18th century to demonstrate this relationship, leading to the formulation of this law.

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• 2.

### Which law explains the mechanism of a pressure cooker?

• A.

Boyle's Law

• B.

Charles' Law

• C.

Gay - Lussac's Law

• D.

Ideal Gas Law

C. Gay - Lussac's Law
Explanation
Gay-Lussac's Law, also known as the pressure-temperature law, explains the mechanism of a pressure cooker. This law states that the pressure of a gas is directly proportional to its temperature, assuming the volume and amount of gas remain constant. In a pressure cooker, as the temperature increases, the pressure inside the cooker also increases. This allows the food to cook faster as the higher pressure raises the boiling point of water, resulting in shorter cooking times. Therefore, Gay-Lussac's Law is the appropriate law to explain the mechanism of a pressure cooker.

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• 3.

### What will happen to the volume of a confined gas as the pressure increases if the temperature of the gas is kept constant?

• A.

The volume increases

• B.

The volume decreases

• C.

The volume remains the same

• D.

There is no significant change

B. The volume decreases
Explanation
When the pressure of a confined gas is increased while keeping the temperature constant, the volume of the gas decreases. This is known as Boyle's law, which states that the volume of a gas is inversely proportional to its pressure when the temperature remains constant. As the pressure increases, the gas particles are forced closer together, resulting in a decrease in volume.

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• 4.

• A.

Option 1

• B.

Option 2

• C.

Option 3

• D.

Option 4

A. Option 1
• 5.

### If a balloon full of warm air was placed in a refrigerator, the balloon would ______.

• A.

Get larger

• B.

Remains the same

• C.

Get smaller

• D.

Burst

C. Get smaller
Explanation
When a balloon full of warm air is placed in a refrigerator, the temperature inside the refrigerator is much colder than the warm air inside the balloon. As a result, the air molecules inside the balloon lose energy and slow down, causing them to contract and occupy less space. This contraction leads to a decrease in the volume of the balloon, causing it to get smaller.

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• 6.

### What property of gas is best described when a gas tank is filled and more gases can still be added?

• A.

Gas is elastic

• B.

Gas can be compressed

• C.

Gas diffuses

• D.

Gas exerts pressure

B. Gas can be compressed
Explanation
The correct answer is "gas can be compressed". This is because when a gas tank is filled and more gases can still be added, it indicates that the gas molecules can be further compressed within the tank. Gas molecules have a lot of empty space between them, and they can be easily compressed into a smaller volume. This property of gases allows them to occupy any available space and be compressed under pressure.

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• 7.

### Which of the following activities involves the application of gas pressure?

• A.

Burning gas

• B.

Inflating balloons

• C.

Cooking food

• D.

Gas exerts pressure

B. Inflating balloons
Explanation
Inflating balloons involves the application of gas pressure. When we blow air into a balloon, the gas molecules inside the balloon collide with the walls of the balloon, creating pressure. As more air is blown into the balloon, the pressure increases, causing the balloon to expand. This is because the gas molecules push against the walls of the balloon, exerting pressure on them. Therefore, inflating balloons is an activity that involves the application of gas pressure.

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• 8.

### A balloon filled with helium occupies 15 L at 400 K. What will be the volume of the helium balloon if the temperature of the helium is increased to 600 K? (Assume that the pressure is held constant)

• A.

10 L

• B.

22.5 L

• C.

32.5 L

• D.

50 L

B. 22.5 L
Explanation
When the temperature of a gas is held constant, the volume of the gas is directly proportional to the temperature. This is known as Charles's Law. In this case, the initial volume of the helium balloon is 15 L at 400 K. If the temperature is increased to 600 K, the volume of the balloon will also increase proportionally. Using the formula V1/T1 = V2/T2, where V1 is the initial volume, T1 is the initial temperature, V2 is the final volume, and T2 is the final temperature, we can solve for V2. Plugging in the values, we get (15 L)/(400 K) = V2/(600 K). Solving for V2, we find that the volume of the helium balloon will be 22.5 L.

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• 9.

• A.

Option 1

• B.

Option 2

• C.

Option 3

• D.

Option 4

A. Option 1
• 10.

### Gas molecules are trapped in the space below the piston. The piston can move up and down in the cylinder. The cylinder is resting on a hot plate. If the hot plate is turned on what would happen to the volume of the gas?

• A.

The volume increases

• B.

The volume decreases

• C.

The volume remains the same

• D.

There is no significant change

A. The volume increases
Explanation
When the hot plate is turned on, it increases the temperature of the gas molecules trapped below the piston. As the temperature increases, the gas molecules gain more kinetic energy and move faster. This increased motion causes the gas molecules to collide more frequently with the walls of the cylinder, including the piston. The increased collisions exert more force on the piston, causing it to move upwards and increasing the volume of the gas. Therefore, the correct answer is that the volume increases.

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• 11.

### Suppose the piston is fastened so that it could not move. When the hot plate is turned on, what would happen to the pressure of the gas? It will

• A.

Decrease

• B.

Increase

• C.

Stay the same

• D.

None of these

B. Increase
Explanation
When the hot plate is turned on, the temperature of the gas inside the piston would increase. According to the ideal gas law, an increase in temperature leads to an increase in pressure, assuming the volume and the amount of gas remain constant. Therefore, in this scenario, the pressure of the gas would increase.

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• 12.

### What will happen to the gas pressure as the temperature increases if the amount and volume of gas were kept constant?

• A.

The pressure increases

• B.

The pressure decreases

• C.

There is no significant change

• D.

The gas pressure remains the same

A. The pressure increases
Explanation
When the temperature of a gas increases, the molecules of the gas gain more kinetic energy and move faster. This increased motion leads to more frequent and forceful collisions with the walls of the container, resulting in an increase in pressure. Therefore, as the temperature increases, the gas pressure also increases.

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• 13.

### What can be inferred regarding the relationship between pressure and volume as shown in the Line graph below?

• A.

Volume is independent of pressure.

• B.

Volume is directly proportional to the pressure.

• C.

â€‹â€‹â€‹â€‹â€‹â€‹Volume is inversely proportional to the pressure.

• D.

â€‹â€‹â€‹â€‹â€‹â€‹Volume is not affected by a change in pressure

C. â€‹â€‹â€‹â€‹â€‹â€‹Volume is inversely proportional to the pressure.
Explanation
The line graph shows that as the pressure increases, the volume decreases, and vice versa. This indicates an inverse relationship between pressure and volume. As one variable increases, the other variable decreases, and vice versa. Therefore, it can be inferred that volume is inversely proportional to pressure.

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• 14.

### What will happen to the volume of the gas sample as temperature increases from 100 K to 150K?

• A.

Volume of the gas increases

• B.

Volume of the gas remains the same

• C.

Volume of the gas decreases

• D.

Volume of the gas cannot be determined

A. Volume of the gas increases
Explanation
As temperature increases, the kinetic energy of gas molecules also increases. This causes the gas molecules to move faster and collide with each other and the walls of the container more frequently and with greater force. Consequently, the gas molecules occupy a larger volume, leading to an increase in the volume of the gas sample.

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• 15.

• A.

1 L

• B.

2 L

• C.

3 L

• D.

4 L

C. 3 L
• 16.

### A gas sample occupies a volume of 100 mL at a pressure of 3.0 atm at 20.00C. What is the new pressure if the volume is increased to 150 mL at constant temperature?

• A.

5.0 atm

• B.

4.5 atm

• C.

2.0 atm

• D.

1.5 atm

C. 2.0 atm
Explanation
According to Boyle's Law, at constant temperature, the pressure and volume of a gas are inversely proportional. This means that as the volume increases, the pressure decreases. In this case, the volume is increased from 100 mL to 150 mL, which means the pressure will decrease. The new pressure can be calculated using the formula P1V1 = P2V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume. Plugging in the given values, we get (3.0 atm)(100 mL) = (P2)(150 mL). Solving for P2, we find that the new pressure is 2.0 atm.

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• 17.

### All the following steel containers have the same size. Which of the following containers has the highest pressure?

• A.

1 mole

• B.

2 mole

• C.

3 mole

• D.

4 mole

D. 4 mole
Explanation
The pressure of a gas is directly proportional to the number of moles of gas present, assuming the volume and temperature are constant. Therefore, the container with 4 moles of gas will have the highest pressure compared to the containers with fewer moles of gas.

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• 18.

### How can you possibly prove that gases have negligible mass?

• A.

• B.

Ask two persons to hold a box filled with air

• C.

Feel the weight of the samples on both hands

• D.

Put a balloon on a balance which can measure up the nearest hundredths of a gram before and after you fill it with air

D. Put a balloon on a balance which can measure up the nearest hundredths of a gram before and after you fill it with air
Explanation
By putting a balloon on a balance before and after filling it with air, you can measure the change in weight. Since gases have negligible mass, the weight of the balloon should remain almost the same before and after filling it with air. This can be proven through the equation of weight, which states that weight is equal to mass multiplied by the acceleration due to gravity. Since the mass of the gas is negligible, the change in weight should also be negligible, supporting the claim that gases have negligible mass.

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• 19.

### A gas sample occupies a volume of 125 mL at a pressure of 720 torr at 20.00C. What is the new pressure if the volume is increased to 250 mL at the same temperature?

• A.

1440 torr

• B.

720 torrr

• C.

360 torr

• D.

375 torr

C. 360 torr
Explanation
According to Boyle's Law, the product of pressure and volume is constant at constant temperature. Therefore, if the volume is doubled, the pressure must be halved to maintain the same product. In this case, the volume is increased from 125 mL to 250 mL, so the pressure must be halved from 720 torr to 360 torr.

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• 20.

### Which of the following is a disaccharide?

• A.

Fructose

• B.

Galactose

• C.

Glucose

• D.

Sucrose

D. Sucrose
Explanation
Sucrose is a disaccharide because it is composed of two monosaccharides, glucose and fructose, joined together by a glycosidic bond. It is commonly found in table sugar and is a common sweetener in many foods and beverages. Fructose, galactose, and glucose are all monosaccharides, which means they consist of a single sugar unit.

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• 21.

### Which of the following pairs of monosaccharide form lactose sugar?

• A.

Glucose + Fructose

• B.

Glucose + Galactose

• C.

Glucose + Glucose

• D.

Fructose + Galactose

B. Glucose + Galactose
Explanation
Lactose sugar is formed by the combination of glucose and galactose. Lactose is a disaccharide composed of these two monosaccharides. Glucose is a common monosaccharide found in many sugars, while galactose is another monosaccharide that is less common but still found in certain sugars. When glucose and galactose combine, they form the disaccharide lactose. Therefore, the correct answer is glucose + galactose.

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• 22.

### The molecular formula for a monosaccharide is C6H12O6. Which of the following is an isomer of glucose?

• A.

Fructose

• B.

Lactose

• C.

Maltose

• D.

Sucrose

A. Fructose
Explanation
Fructose is an isomer of glucose because both molecules have the same molecular formula, C6H12O6, but they have different structural arrangements. Isomers are compounds that have the same molecular formula but different structural formulas, resulting in different chemical properties. In the case of fructose and glucose, they have the same number and types of atoms but differ in the arrangement of their atoms, particularly the position of the hydroxyl groups. Therefore, fructose is an isomer of glucose.

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• 23.

### Which of the following is a major source of Carbohydrates?

• A.

Apple

• B.

Milk

• C.

Potato

• D.

Vegetables

C. Potato
Explanation
Potato is a major source of carbohydrates because it is a starchy vegetable that contains a high amount of complex carbohydrates. These carbohydrates are the primary source of energy for the body and are essential for various bodily functions. Potatoes are also rich in fiber, vitamins, and minerals, making them a nutritious choice.

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• 24.

### The end product of proteins digested in our body is amino acids. Which of the following is the function of amino acids in the body?

• A.

Make fatty acids

• B.

Make skin, hair, enzymes and muscles

• C.

Make vitamins

• D.

Produce quick energy

B. Make skin, hair, enzymes and muscles
Explanation
Amino acids are the building blocks of proteins, and proteins are essential for the growth and repair of tissues in the body. Therefore, the function of amino acids in the body is to make skin, hair, enzymes, and muscles.

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• 25.

### When digesting a complex carbohydrate, water is added and simple sugar is produced. Which of the following describes the process?

• A.

Condensation

• B.

Dehydration

• C.

Hydrolysis

• D.

Photosynthesis

C. Hydrolysis
Explanation
Hydrolysis is the correct answer because it is the process of breaking down a complex molecule into simpler components by adding water. In the context of digesting a complex carbohydrate, hydrolysis occurs when water is added to the carbohydrate, breaking it down into simple sugars. This process is essential for the body to absorb and utilize the energy from carbohydrates. Condensation, dehydration, and photosynthesis are not relevant to the given question.

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• 26.

### Which of the following is a polysaccharide?

• A.

Cellulose

• B.

Fructose

• C.

Glucose

• D.

Lactose

A. Cellulose
Explanation
Cellulose is a polysaccharide because it is a complex carbohydrate made up of many glucose molecules bonded together. It is the main component of plant cell walls and provides structural support. Fructose, glucose, and lactose are all monosaccharides or simple sugars, which are not considered polysaccharides.

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• 27.

### The formula of the compound shown below is an example of

• A.

Amino acid

• B.

A fat

• C.

A mineral

• D.

A simple sugar

A. Amino acid
Explanation
The compound shown in the question is an example of an amino acid. Amino acids are organic compounds that contain both an amino group (-NH2) and a carboxyl group (-COOH) attached to the same carbon atom. They are the building blocks of proteins and play important roles in various biological processes.

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• 28.

### Which of the following statements is/are true about proteins?             I. They are polymers of amino acids. II. They are insoluble molecules that are composed of carbon, hydrogen and oxygen. III. They are molecules from aldehydes and ketones containing numerous hydroxyl groups.

• A.

I only

• B.

I and II only

• C.

I and III only

• D.

II and III

C. I and III only
Explanation
Proteins are polymers of amino acids, which makes statement I true. However, statement II is incorrect because proteins are soluble molecules and not insoluble. Statement III is also incorrect because proteins are not derived from aldehydes and ketones with numerous hydroxyl groups.

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• 29.

### Malou conducted an activity to determine what types of biomolecules are present in the three           unknown substances given in the table below. Which of the following statements is correct?

• A.

Substance O is a lipid while substance M is a simple sugar.

• B.

Substance N is a starch while substance O is a simple sugar.

• C.

Substances M and N are proteins while substance O is not.

• D.

Substance M is a simple sugar, while substances N and O are not.

D. Substance M is a simple sugar, while substances N and O are not.
Explanation
The correct answer is that Substance M is a simple sugar, while substances N and O are not. This conclusion can be drawn from the information provided in the question, which states that Malou conducted an activity to determine the types of biomolecules present in the substances. Based on the results of the activity, it can be inferred that Substance M contains simple sugars, while substances N and O do not contain simple sugars. The question does not provide any information about the presence of lipids, starch, or proteins in the substances, so the other statements cannot be determined to be correct.

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• 30.

### The table below shows the different components of organic compounds in living organisms.  Which element is found in protein & nucleic acid but not in carbohydrates, fats and oils?

• A.

Carbon

• B.

Hydrogen

• C.

Nitrogen

• D.

Oxygen

C. Nitrogen
Explanation
Nitrogen is found in proteins and nucleic acids, which are essential components of living organisms. Carbohydrates, fats, and oils do not contain nitrogen. Therefore, nitrogen is the element that is found in proteins and nucleic acids but not in carbohydrates, fats, and oils.

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• 31.

### Which disaccharide will be formed from these monosaccharides shown in the drawing below?

• A.

Galactose

• B.

Lactose

• C.

Maltose

• D.

Sucrose

D. Sucrose
Explanation
Sucrose is the correct answer because it is formed from the combination of glucose and fructose, which are the monosaccharides shown in the drawing. Galactose and lactose are not formed from these monosaccharides, and maltose is formed from two glucose molecules.

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• 32.

### Which of the following evidence of chemical change explains the curdling of milk?

• A.

Evolution of gas

• B.

Formation of precipitate

• C.

Change in temperature

• D.

Production of heat and light

B. Formation of precipitate
Explanation
The curdling of milk is a clear example of a chemical change. When milk curdles, it forms a precipitate, which is a solid substance that separates from the liquid. This indicates a chemical reaction has occurred, causing a change in the composition of the milk. The formation of a precipitate is a common evidence of a chemical change, as it involves the creation of a new substance with different properties than the original substances.

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• 33.

### Which of the following would most likely happen when substances undergo chemical reactions?

• A.

No new substances will be formed.

• B.

New substances are formed which are heavier than that of the reactants.

• C.

New substances are formed with the same set of properties as that of the reactants

• D.

New substances are formed with the different set of properties as that of the reactants

D. New substances are formed with the different set of properties as that of the reactants
Explanation
During a chemical reaction, new substances are formed with different properties than the reactants. This is because the atoms and molecules rearrange and bond in different ways, leading to the formation of new compounds with unique chemical and physical properties. This is a fundamental characteristic of chemical reactions, as they involve the transformation of substances into different substances with distinct characteristics.

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• 34.

### Which of the following laws conforms a balanced chemical reaction?

• A.

Law of relativity

• B.

Law of conservation of mass

• C.

Law of inertia

• D.

Law of definite proportion

B. Law of conservation of mass
Explanation
The law of conservation of mass states that in a chemical reaction, matter is neither created nor destroyed. This means that the total mass of the reactants must be equal to the total mass of the products. This law ensures that a chemical reaction is balanced, as it requires the same number of atoms of each element on both sides of the reaction equation. Therefore, the law of conservation of mass is the correct answer as it conforms to a balanced chemical reaction.

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• 35.

### Given the reaction:  Potassium chlorate (KClO3) when heated produces potassium chloride (KCl) and oxygen gas (O2). Which of the following equations represents the above reaction?

• A.

KClO3(s)   —->        KCl  + O2

• B.

2KClO3(s)    —>      2KCl(s) + 3O2↑

• C.

2KClO3   —>         2KCl  + O2

• D.

KClO3    —>        KCl  + 3O2

B. 2KClO3(s)    —>      2KCl(s) + 3O2↑
Explanation
The equation 2KClO3(s) â†’ 2KCl(s) + 3O2 represents the given reaction because it shows that when potassium chlorate is heated, it decomposes into potassium chloride and oxygen gas. The coefficients in the equation indicate the ratio of the reactants and products, with 2 moles of potassium chlorate producing 2 moles of potassium chloride and 3 moles of oxygen gas. The upward arrow indicates the release of oxygen gas as a product of the reaction.

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• 36.

### Given the reaction:  Potassium chlorate (KClO3) when heated produces potassium chloride (KCl) and oxygen gas (O2). Potassium chlorate (KClO3) had undergone what type of reaction?

• A.

Combination

• B.

Decomposition

• C.

Double displacement

• D.

Single replacement

B. Decomposition
Explanation
The given reaction involves the breakdown of a single compound, potassium chlorate (KClO3), into two simpler substances, potassium chloride (KCl) and oxygen gas (O2). This type of reaction is known as decomposition, where a compound is broken down into its constituent elements or simpler compounds.

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• 37.

### Which metal is most reactive?

• A.

Copper

• B.

Rubidium

• C.

Strontium

• D.

B. Rubidium
Explanation
Rubidium is the most reactive metal among the options given. This is because rubidium is located in Group 1 of the periodic table, also known as the alkali metals. Group 1 metals are highly reactive due to their low ionization energies and tendency to lose one electron to form a positive ion. Rubidium has a larger atomic radius and lower ionization energy compared to the other metals listed, making it more likely to react with other elements or compounds.

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• 38.

### What would be the balanced equation for the combustion of butane, a lighter fluid?

• A.

C4H10 + O2     —> 4CO2   + 5H2O

• B.

2C4H10 + 13O2   —> 8CO2   + 10H2O

• C.

C4H10 + O2 —> CO2   + 5H2O

• D.

C4H10 + O2   —> 4CO2   + H2O

B. 2C4H10 + 13O2   —> 8CO2   + 10H2O
Explanation
The balanced equation for the combustion of butane, a lighter fluid, is 2C4H10 + 13O2 -> 8CO2 + 10H2O. This equation is balanced because there are equal numbers of atoms on both sides of the equation. The coefficients in front of each molecule represent the number of molecules needed to balance the equation. In this case, 2 molecules of butane react with 13 molecules of oxygen to produce 8 molecules of carbon dioxide and 10 molecules of water.

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• 39.

### Which of the following is the correct balanced chemical equation for the combustion of natural gas (Methane)?

• A.

CH4  + 2O2 —>  CO2 +   2H2O

• B.

2CH4  +  O2 —>  2CO2 +  4H2O

• C.

2CH4  + 2O2 —>  2CO2 + 2H2O

• D.

2CH4  + 4O2 —>  2CO2 + H2O

A. CH4  + 2O2 —>  CO2 +   2H2O
• 40.

### NaCl + AgNO3 --> AgCl   +. NaNO3 is an example of what type of chemical reaction?

• A.

Combination

• B.

Decomposition

• C.

Double displacement

• D.

Single replacement

C. Double displacement
Explanation
The given chemical equation shows the reaction between NaCl and AgNO3, which results in the formation of AgCl and NaNO3. This type of reaction is known as a double displacement reaction. In this reaction, the cations (Na+ and Ag+) and the anions (Cl- and NO3-) exchange places, forming two new compounds. Double displacement reactions typically occur between two compounds in an aqueous solution and result in the formation of a precipitate, gas, or water.

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• 41.

### Which of the following would most likely happen when sodium hydroxide (NaOH) solution and copper sulfate (CuSO4) are combined?

• A.

Gas will evolve

• B.

Precipitate will form

• C.

Temperature will change

• D.

No reaction

B. Precipitate will form
Explanation
When sodium hydroxide (NaOH) solution and copper sulfate (CuSO4) are combined, a precipitate will form. This is because sodium hydroxide reacts with copper sulfate to form copper hydroxide, which is insoluble in water and therefore precipitates out of the solution.

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• 42.

### Sulfuric acid (H2SO4) is produced from sulfur (S), oxygen (O), and water (H2O). Which of the following is the correct balanced chemical equation for the production of sulfuric acid?

• A.

SO3   +. H2O —> H2SO4

• B.

2SO3   +. 3H2O —> 3H2SO4

• C.

3SO3   +. H2O —> 3H2SO4

• D.

2SO3   +. H2O —> 2 H2SO4

A. SO3   +. H2O —> H2SO4
Explanation
The correct balanced chemical equation for the production of sulfuric acid is SO3 + H2O -> H2SO4. This equation shows that one molecule of sulfur trioxide (SO3) reacts with one molecule of water (H2O) to produce one molecule of sulfuric acid (H2SO4). The coefficients in front of the molecules indicate the stoichiometric ratio of the reactants and products, ensuring that the equation is balanced.

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• 43.

### Why does the rate of reaction increase when iron filings are used instead of iron nail in a reaction with hydrochloric acid?

• A.

Iron filings act as a catalyst.

• B.

Iron filings have higher density.

• C.

Iron filings have higher surface area.

• D.

Iron filings can increase the temperature of the reaction.

C. Iron filings have higher surface area.
Explanation
Iron filings have a higher surface area compared to an iron nail. When a reaction occurs between iron and hydrochloric acid, the surface area of the iron determines the rate at which the reaction takes place. The higher the surface area, the more contact the iron has with the acid, leading to an increased rate of reaction. Therefore, using iron filings instead of an iron nail increases the rate of reaction because of the higher surface area.

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• 44.

### Five grams of iron fillings were placed in beakers A, B, C, and D. Which beaker will have the        fastest rate of reaction? Beaker ……

• A.

A

• B.

B

• C.

C

• D.

D

D. D
Explanation
Beaker D will have the fastest rate of reaction. This is because the rate of reaction is influenced by the surface area of the reactants. In this case, all the beakers have the same amount of iron fillings (5 grams), but beaker D has the largest surface area because it has the smallest volume. As a result, the iron fillings in beaker D will have more contact with the surrounding reactants, leading to a faster rate of reaction.

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• 45.

### Which factor affects the rate of the reaction below?

• A.

Surface area of the reactants

• B.

Concentration of the reactants

• C.

Use of catalyst

• D.

Nature of the reactants

B. Concentration of the reactants
Explanation
The concentration of the reactants affects the rate of the reaction. When the concentration of the reactants is higher, there are more particles available to collide and react with each other, leading to an increase in the rate of the reaction. On the other hand, when the concentration is lower, there are fewer particles available for collision, resulting in a slower rate of reaction. Therefore, the concentration of the reactants directly influences the rate at which the reaction takes place.

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• 46.

### Milk becomes sour more quickly on a hot summer’s day. Which factor affects the spoilage of milk?

• A.

Catalyst

• B.

Concentration

• C.

Surface area

• D.

Temperature

D. Temperature
Explanation
Temperature affects the spoilage of milk because higher temperatures provide an ideal environment for the growth of bacteria and other microorganisms that cause milk to spoil. Heat speeds up the chemical reactions that occur in the milk, causing it to sour more quickly. Therefore, on a hot summer's day, the increased temperature accelerates the spoilage process of milk.

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• 47.

### Refer to the following changes which might be made from the reaction between dilute hydrochloric acid (HCl) and marble chips (CaCO3).             I. Increasing the temperature             II. Using larger marble chips             III. Using smaller marble chips             IV.  Decreasing the concentration of acid Which change(s) would increase the rate of the reaction?

• A.

I only

• B.

I and II

• C.

I and III

• D.

I and IV

C. I and III
Explanation
Increasing the temperature would increase the rate of the reaction because it provides more energy to the particles, causing them to move faster and collide more frequently, leading to more successful collisions and a higher reaction rate. Using smaller marble chips would also increase the rate of the reaction because they have a larger surface area compared to larger chips, providing more area for the acid to react with and increasing the rate of collisions between the acid and the chips.

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• 48.

### Refer to the following changes which might be made from the reaction between dilute hydrochloric acid (HCl) and marble chips (CaCO3).             I. Increasing the temperature             II. Using larger marble chips             III. Using smaller marble chips             IV.  Decreasing the concentration of acid Which change(s) would decrease the rate of the reaction?

• A.

II only

• B.

I and III

• C.

II and III

• D.

II and IV

D. II and IV
Explanation
Using larger marble chips would decrease the rate of the reaction because larger marble chips have a smaller surface area, which reduces the number of collisions between the acid and the marble chips. Decreasing the concentration of acid would also decrease the rate of the reaction because there would be fewer acid particles available to react with the marble chips.

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• 49.

### Ammonia is used to make fertilizers. It is made from nitrogen and hydrogen. The graph below shows the percentage of ammonia that can be made from the same mixture of nitrogen and hydrogen at different temperatures and pressures. Which of the following conclusions is correct based on the information in the graph?

• A.

The percentage of ammonia increases as both the pressure and temperature decrease.

• B.

The percentage of ammonia increases as both the pressure and temperature increase.

• C.

The percentage of ammonia increases as the pressure increases and temperature decreases.

• D.

The percentage of ammonia increases as the pressure decreases and temperature increases.

B. The percentage of ammonia increases as both the pressure and temperature increase.
Explanation
The correct answer is that the percentage of ammonia increases as both the pressure and temperature increase. This can be determined by observing the trend in the graph, which shows that as both the pressure and temperature increase, the percentage of ammonia that can be made from the mixture of nitrogen and hydrogen also increases.

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• 50.

### Ammonia is used to make fertilizers. It is made from nitrogen and hydrogen. The graph below shows the percentage of ammonia that can be made from the same mixture of nitrogen and hydrogen at different temperatures and pressures. Which of the following pressure and temperature conditions could increase the yield of ammonia?

• A.

Low temperature and low pressure

• B.

High temperature and low pressure

• C.

Low temperature and high pressure

• D.

Both high temperature and pressure