Question

this passage describes a chemical reaction. read the passage. then, answer the question below.

the cheesemaking process sometimes includes a step called lactic acid fermentation. this step occurs when a certain type of bacteria is added to milk. the bacteria form lactic acid (c₃h₆o₃) by combining water (h₂o) and lactose (c₁₂h₂₂o₁₁) in the milk. when lactic acid forms, the milk’s proteins clump into curds that can later be used to make many types of cheese.

in the chemical reaction described in the passage, which of the following are products?
select all that apply.

lactose (c₁₂h₂₂o₁₁)
water (h₂o)
lactic acid (c₃h₆o₃)

Explanation:

In a chemical reaction, reactants are the substances that react (are used up), and products are the substances formed. The passage says bacteria form lactic acid by combining water and lactose. So water ($\ce{H_2O}$) and lactose ($\ce{C_{12}H_{22}O_{11}}$) are reactants (they are combined), and lactic acid ($\ce{C_3H_6O_3}$) is the product (formed from them). The initial selections of lactose and water as products are incorrect; only lactic acid is the product.

Answer:

lactic acid ($\ce{C_3H_6O_3}$)