3) A respeito das substâncias denominadas ácidos, um estudante anotou as seguintes características:*5 pontosa) I e IIb) I e IIIc) I e IVd) II e IIIe) III e IV

To address this question, the student has likely compiled a list of characteristics to identify acids, such as their sour taste, ability to turn litmus paper red, reactivity with bases, and their ability to conduct electricity in solution. The question might be asking the student to select which of these characteristics correspond with the definition of acids.

1. Break Down the Problem

• Identify the characteristics of acids.
• Match them with the given options (I, II, III, IV).

2. Relevant Concepts

• Acids are substances that typically donate protons (H⁺ ions) in a solution.
• Common characteristics of acids include:
  • I: Sour taste
  • II: Turns blue litmus paper red
  • III: Reacts with metals
  • IV: Conducts electricity (due to ionization)

3. Analysis and Detail

• Evaluate each listed characteristic against common properties of acids.
• Determine which combinations (a-e) include the characteristics that properly represent acids.

4. Verify and Summarize

• Review each of the provided combinations with the characteristics of acids to determine the accurate selections.

Final Answer

The correct combinations would encompass characteristics I (Sour taste) and II (Turns blue litmus paper red), which are commonly recognized features of acids. Therefore, the answer would be a) I e II.