Which change is chemical?(1 point)
Responses
water freezing: liquid water becoming solid water
water freezing: liquid water becoming solid water
water evaporating: liquid water becoming gaseous water
water evaporating: liquid water becoming gaseous water
water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules
water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules
water boiling: solid water becoming gaseous water
water boiling: solid water becoming gaseous water
Which number remains unchanged during photosynthesis?(1 point)
Responses
the number of carbon dioxide molecules
the number of carbon dioxide molecules
the number of carbon atoms
the number of carbon atoms
the number of water molecules
the number of water molecules
the number of glucose molecules
the number of carbon atoms
In a chemical reaction, which aspect of the reactants changes?(1 point)
Responses
total mass
total mass
nuclei
nuclei
arrangement of the atoms
arrangement of the atoms
name of each element
arrangement of the atoms
A young snake eats and digests a mouse. The increase in the snake’s mass equals(1 point)
Responses
only the mass of the mouse
only the mass of the mouse
the mass of the mouse plus the original mass of the snake.
the mass of the mouse plus the original mass of the snake.
the mass of the mouse minus the mass of waste produced by the snake.
the mass of the mouse minus the mass of waste produced by the snake.
the mass of the mouse plus the mass of waste produced by the snake.
the mass of the mouse plus the mass of waste produced by the snake.
Cellular respiration transforms glucose and oxygen into carbon dioxide, water, and energy.
C6H12O6 + 6O2 → 6CO2 + ?H2O + Energy
Based on the law of conservation of matter, what is the missing coefficient for water?
(1 point)
Responses
2
2
8
8
4
4
6
6
6
The change that is chemical is water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules.
To determine the correct answer, we can analyze the different changes and identify if they involve a chemical reaction.
1. Water freezing: This is a physical change where liquid water molecules lose energy and arrange themselves in a more ordered structure to form solid ice. No new substances are formed, so it is not a chemical change.
2. Water evaporating: This is also a physical change where liquid water absorbs enough energy to convert into gaseous water vapor. Again, no new substances are formed, so it is not a chemical change.
3. Water undergoing electrolysis: This is a chemical change where an electric current is passed through water, causing it to break down into its constituent elements, oxygen, and hydrogen. This process involves the formation of new substances, so it is a chemical change.
4. Water boiling: This is a physical change where solid ice, which is essentially frozen water, absorbs enough energy to convert directly into gaseous water vapor. Similar to evaporation, no new substances are formed, making it a physical change.
Based on this analysis, the only change involving the formation of new substances is water undergoing electrolysis, making it the correct answer.