Question

1. a compound is made of materials that are chemically combined in a fixed ratio and later cannot be separated. mixtures often contain compounds. for example, salt water contains two compounds, nacl and h₂o. which of the following statements is true of mixtures?

a. substances in a mixture cannot be separated after combining.
b. each substance in a mixture develops new chemical properties.
c. each substance in a mixture keeps its individual properties.
d. substances in a mixture exchange electrons.

1. chemical equations show the ratio of reactants and products involved in a chemical reaction. for example, 2 h₂ + o₂ → 2 h₂o. how do balanced equations satisfy the law of conservation of mass?

a. the number of reactant molecules equals the number of product molecules.
b. every atom present in the reactants is also present in the products.
c. the number of reactant molecules adds up to the number of product molecules.
d. the energy stored in bonds before and after the reaction is the same.

1. molecular models of a single carbon atom, a two - atom molecule of oxygen, and a molecule of carbon dioxide are shown.

image of molecular models: a single carbon atom + a two - atom oxygen molecule → a carbon dioxide molecule
which chemical equation best represents the reaction shown in the model?
a. 2c + o₂ → 2co₂
b. h + o₂ → h₂o
c. c + o₂ → co₂
d. co₂ → c + o₂

1. special structures in the cells of plants capture sunlight energy to power photosynthesis. what materials must plants obtain from their environment to perform photosynthesis?

a. sunlight, oxygen, and carbon dioxide
b. sunlight, water, and carbon dioxide
c. sunlight, water, and oxygen
d. sunlight, carbon dioxide, and simple sugars

Explanation:

Question 3:

Mixtures are physical combinations, so components retain their original properties, can be separated physically, and do not form new substances or exchange electrons.

Question 4:

The Law of Conservation of Mass states matter is not created/destroyed. Balanced equations ensure all reactant atoms appear in products.

Question 5:

The model shows 1 carbon atom reacting with 1 oxygen molecule to form 1 carbon dioxide molecule, matching the balanced equation for this reaction.

Question 6:

The photosynthesis process uses sunlight energy, water (from soil), and carbon dioxide (from air) to produce glucose and oxygen.

Answer:

1. C. Each substance in a mixture keeps its individual properties
2. B. Every atom present in the reactants is also present in the products
3. C. $\text{C} + \text{O}_2

ightarrow \text{CO}_2$

1. B. sunlight, water, and carbon dioxide