The rhyme scheme and rhythm of this stanza contribute to creating an energetic and urgent mood in the poem.
Regarding the second question, the line that best conveys the anxiety and tension present in these stanzas is: "The fate of a nation was riding that night;"
The regular rhyme scheme (ABABCC) and the steady rhythm of the poem reflect the urgency and determination of Paul Revere's ride. The use of rhyme, such as "alarm" and "farm," "fear" and "door," adds a sense of continuity and purpose to the narrative.
This line suggests the gravity of the situation and the immense responsibility that Paul Revere carries as he rides through the night to warn about the approaching British troops. It emphasizes the high stakes and the critical role that Revere plays in the larger context of the nation's fate.