Question

Which change is chemical?(1 point) Responses water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules water freezing: liquid water becoming solid water water freezing: liquid water becoming solid water water boiling: solid water becoming gaseous water water boiling: solid water becoming gaseous water water evaporating: liquid water becoming gaseous water

Answer 1

The change that is chemical is "water undergoing electrolysis: liquid water becoming oxygen and hydrogen molecules."

This process involves breaking the chemical bonds in water (H2O) to produce hydrogen (H2) and oxygen (O2) gases, which is a chemical change. The other processes listed (freezing, boiling, and evaporating) are all physical changes, as they involve changes in state but do not alter the chemical composition of the substance.

Answer 2

Which number remains unchanged during photosynthesis?(1 point) Responses the number of water molecules the number of water molecules the number of glucose molecules the number of glucose molecules the number of carbon atoms the number of carbon atoms the number of carbon dioxide molecules

Answer 3

The number that remains unchanged during photosynthesis is the number of carbon atoms.

Photosynthesis transforms carbon dioxide and water into glucose and oxygen, but the total number of carbon atoms remains constant throughout the process. Each molecule of carbon dioxide contributes one carbon atom to the glucose produced, and therefore the total number of carbon atoms is conserved.

Answer 4

in a chemical reaction, which aspect of the reactants changes?(1 point) Responses nuclei nuclei arrangement of the atoms arrangement of the atoms name of each element name of each element total mass

Answer 5

In a chemical reaction, the aspect of the reactants that changes is the arrangement of the atoms.

During a chemical reaction, the bonds between atoms in the reactants are broken and new bonds are formed, resulting in different molecular arrangements in the products. The identity of the elements (the names) and the total mass remain unchanged due to the law of conservation of mass, while the nuclei (in terms of atomic number and mass) of the atoms do not change.

Answer 6

A young snake eats and digests a mouse. The increase in the snake’s mass equals(1 point) Responses 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 plus the mass of waste produced by the snake. the mass of the mouse plus the mass of waste produced by the snake. only the mass of the mouse only the mass of the mouse the mass of the mouse minus the mass of waste produced by the snake.

Answer 7

The increase in the snake’s mass equals the mass of the mouse minus the mass of waste produced by the snake.

When a snake (or any organism) consumes food, it assimilates nutrients from that food to increase its mass, but it also excretes waste. Therefore, the net increase in mass would take into account the mass of the consumed mouse minus any waste that is produced as a result of the digestion process.

Answer 8

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 6 6 4 4 2 2 8

Answer 9

To determine the missing coefficient for water in the equation for cellular respiration, we can balance the equation according to the law of conservation of matter, which states that the number of atoms of each element must be equal on both sides of the equation.

The unbalanced equation is: \[ \text{C}6\text{H}{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + ?\text{H}_2\text{O} + \text{Energy} \]

Balancing the equation:

1. Carbons:

   • 6 carbons in \( \text{C}6\text{H}{12}\text{O}_6 \) which produce 6 \( \text{CO}_2 \) (balanced).

2. Oxygens:

   • In the reactants, there are 6 \( O_2 \) molecules contributing 12 oxygen atoms (6 x 2 = 12) and 1 glucose molecule contributing 6 oxygen atoms.
   • Total on the left: 12 + 6 = 18 oxygen atoms.
   • On the right, we have \( 6\text{CO}_2 \) which contributes 12 oxygen atoms (6 x 2 = 12).
   • To find the number of \( H_2O \) needed to have 18 oxygen atoms total, we can set up the equation: \[ 12 (from , CO_2) + ? (from , H_2O) = 18 \] This implies that: \[ ? = 18 - 12 = 6. \]

3. Hydrogens:

   • In glucose, there are 12 hydrogen atoms and each water molecule (\( H_2O \)) has 2 hydrogen atoms, so to balance: \[ \text{Number of } H_2O = \frac{12}{2} = 6. \]

Therefore, the missing coefficient for water \( H_2O \) is 6.

The balanced equation is: \[ C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy} \]