ANS:B - zero pressure

A liquid will cease to exist as a liquid at the earth's center. At absolute zero temperature (0 Kelvin or -273.15 degrees Celsius), the molecular momentum of the system theoretically becomes zero. However, even at absolute zero, a substance can exist in different states depending on the pressure. Under normal atmospheric pressure, a substance may solidify or become a gas at absolute zero, but it does not mean that liquids would cease to exist at absolute zero. However, at the earth's center, where extreme pressures exist due to the immense weight of the overlying materials, the pressure is so high that even at absolute zero temperature, matter would exist in a solid or possibly a different state due to the extreme pressure. Therefore, a liquid would cease to exist as a liquid at the earth's center due to the extreme pressure, not necessarily because of the absolute zero temperature alone.