What is the mood in this Pearl? How does the setting contribute to the mood and the conflict?

Do you mean the mood of the story? Initially, before the scorpion stings Kino’s baby, there is a mood of peace and contentment. The "song of the family" gently plays in Kino's head as he rises in a calm morning. After Coyotito gets stung, there is a sense of distress and desperation. This mod becomes persistent throughout the story. It attaches to Kino's life even in the midst of the excitement of finding the great pearl. The mood becomes increasingly tense and desperate as Kino decides to keep his pearl and sell it in the big city.