For #1, the last choice is correct. A geocentric model means that the earth is the center of the universe while all other bodies orbit around it. A heliocentric model means that the sun is the center of the inverse while the other bodies orbit around it. The shared feature is that the other bodies in space move in circular orbits.
For #2, the first answer is correct. When the moon is between the earth and the sun, positions X and Z are being pulled by the moon’s gravitational force, creating high tides at these places. However, positions W and Y are experiencing low tides because no gravitational pull is making them high.
When we inhale, we take in oxygen, and give out carbon dioxide when we exhale. The carbon dioxide we breathe out/exhales enters the atmosphere.
