Which statement best describes the concentration of the solutions made from the dissolved vitamin C tablets? 

• All three solutions have the same concentrations because the amounts of water and solute were the same.

• All three solutions had a concentration of zero because the tablets completely dissolved in the water.

• The solution with the crushed tablet has the lowest concentration because the tablet was in many pieces.

• The solution with the whole tablet has the highest concentration because the tablet was in one piece.

Answer explanation

All three solutions have the same concentrations because the same amount of vitamin C was dissolved in the same volume of water, regardless of the tablet's form (whole or crushed).

Tags

NGSS.MS-PS1-2

Which TWO experiments would examine ways to change the rate of dissolution?

• Use full tablets in each trial and stir each tablet a different number of times when dissolving.

• Use full tablets in each trial, but increase the amount of water used to dilute the Vitamin C tablet.

• Use full tablets in each trial but use a different temperature of water for each container.

• Use a crushed, quartered, and whole tablet, and measure the amount of water evaporated following heating.

• Use crushed, quartered, and whole tablets with varying sizes.

Answer explanation

The correct experiments involve varying the stirring frequency and water temperature, both of which directly affect the dissolution rate. Stirring changes agitation, while temperature influences solubility.

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NGSS.MS-PS1-2

NGSS.MS-PS1-4

Which of the following statements accurately describe the two substances? Choose TWO answers.

• Images A and B are both composed of carbon and oxygen.

• Images A and B are both compounds containing only 2 atoms of oxygen.

• Images A and B are both molecules containing 2 atoms of oxygen.

• Image A is a compound and image B is an element.

• Image A is an element and image B is a compound.

Answer explanation

Images A and B are both molecules containing 2 atoms of oxygen, indicating they are compounds. Additionally, Image A is an element, while Image B is a compound, confirming the correct choices.

Tags

NGSS.MS-PS1-1

An antacid is a medication that is used to help calm heartburn. Some antacid tablets contain two compounds that dissolve when the tablet is placed in water. When these compounds dissolve into solution, they react with each other and form two different compounds, one of which is carbon dioxide (CO­_2­) gas. The person then drinks the dissolved solution. 

This type of antacid tablet is a _________ that dissolves into the _________, water. This is a _________ change.  Once in solution, the _________ react to form a gas which is evidence of a ________ change.

Which terms best complete the sentences?

• chemical

• which is evidence of a ________ change.

• physical

• that dissolves into the _________, water.

• solute

• This is a _________ change. 

• solvent

• Once in solution, the _________ react to form a gas

• molecules

• This type of antacid tablet is a _________

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A glass of lemonade with ice in it sits outside in the Texas summer heat. Before long the ice begins to melt. Which of the following has occurred? Select TWO answers.

• The ice has melted, which is a chemical change.

• The water from the melting ice has been diluted by the lemonade.

• The ice has melted, which is a physical change.

• The water from the melting ice has not diluted the lemonade.

• The lemonade has been diluted by the water from the melting ice.

Answer explanation

The ice melting is a physical change, as it changes state from solid to liquid without altering its chemical composition. Additionally, the water from the melting ice dilutes the lemonade, making it less concentrated.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

The chemical formulas of three substances are recorded.

• C₃H₈O

• C₄H₁₀O

• C₅H₁₂O

• These compounds contain the same​ (a)   because each formula has the same​ (b)   . They are different compounds because they have different​ (c)   .

• elements

• chemical symbol

• chemical formulas

• compounds

• atomic number

• molecules

Answer explanation

The compounds C3H8O, C4H10O, and C5H12O contain the same elements (C, H, O) because they share the same chemical symbols. They are different compounds due to their distinct chemical formulas, indicating different molecular structures.

Tags

NGSS.MS-PS1-1

Glucose is a simple sugar with the molecular formula C₆H₁₂O₆. It contains elements that can be found in the Periodic Table. Which option correctly identifies the type and number of each atom found in glucose?

• Glucose contains 6 atoms of carbon and 18 atoms of holmium.

• Glucose contains 12 atoms of cobalt and 12 atoms of hydrogen.

• Glucose contains 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.

• Glucose contains 24 atoms of carbon, 24 atoms of hydrogen, and 24 atoms of oxygen.

Answer explanation

The correct choice identifies glucose as having 6 carbon (C), 12 hydrogen (H), and 6 oxygen (O) atoms, matching its molecular formula C6H12O6. Other options incorrectly list the number or type of atoms.

Tags

NGSS.MS-PS1-1

Erika is making a saltwater solution to remove ice from her driveway.  She pours salt into a big bucket of water, but most of it sinks to the bottom. 

 

What is the simplest way to get the salt to dissolve?

• Stir the solution with a stick so the salt will dissolves.

• Add ice to cool the salt even more so the salt dissolves.

• Crush the granules of salt into a finer powder.

• Heat the water so the salt dissolves and then cool it back down again.

Answer explanation

Stirring the solution helps distribute the salt throughout the water, increasing its contact with the water and allowing it to dissolve more effectively. This is the simplest and quickest method to achieve dissolution.

In an experiment, students were given the task of dissolving NaCl in water to create aqueous solutions.

 

Student 1 dissolved whole NaCl tablets in 20°C water.

Student 2 dissolved crushed NaCl tablets in 20°C water.

Student 3 dissolved crushed NaCl tablets in 30°C water.

Student 4 dissolved whole NaCl tablets in 10°C water and stirred the mixture.

 

Based on each student’s experimental setup, which student completed the task fastest?

• Student 1 because the tablets had the lowest surface area.

• Student 2 because the tablet shad the highest surface area.

• Student 3 because the tablets the highest surface area and temperature.

• Student 4 because the tablets had the lowest surface area and temperature.

Answer explanation

Student 3 completed the task fastest because they used crushed NaCl tablets, which have a higher surface area, and dissolved them in warmer 30°C water, enhancing the dissolution rate compared to the other setups.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Each of these options is either an element or a compound. Which are elements? Select all correct answers.

• A molecule with two oxygen atoms

• A molecule with two phosphorus atoms and five oxygen atoms

• An atom of Krypton

• A molecule composed of more than one type of atom

• A molecule composed of one type of atom

Answer explanation

Elements are pure substances made of one type of atom. The correct answers include: a molecule with two oxygen atoms (O2), an atom of Krypton (Kr), and a molecule composed of one type of atom, which can also be an element.

Tags

NGSS.MS-PS1-1