The internet is rife with searches for downloadable PDFs of answer keys. While having the answers is useful, relying on them to simply fill in blanks is a pedagogical trap known as "illusions of competence." This occurs when a student looks at an answer, understands it in the moment, and believes they have mastered the material.
A hallmark of a comprehensive study is understanding how spheres interact. Ask "two-sphere" questions: earth science a comprehensive study answer key