First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It gives a general idea about the effect of temperature on the chemical reaction. It does not need any other sentence for context. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with 'However', which is a conjunction and needs prior context. Paragraph 3 starts with 'This', which is a pronoun that refers back to something else. Paragraph 4 starts with 'Consequently', which is also a conjunction and needs prior context.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main idea. It gives a conclusion about the role of temperature in the reaction. It uses the word 'Consequently', which signals that this is the final point.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it uses the connector 'However'. This shows a contrast between the initial observation and the new finding. This follows the Contrast rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it continues the idea of acceleration. It explains more about the acceleration mentioned in Paragraph 2. This follows the Logical Order rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shows the conclusion from the acceleration discussed. The word 'Consequently' shows that this is the result of the previous information. This follows the Cause and Effect Relationship rule.