Question

which statement best explains why earth’s outer core is in liquid form?
○ the iron-nickel alloy melts due to hot temperatures.
○ the outer core has a tarry consistency.
○ this region is less dense when compared to the mantle
○ this region is under extreme pressure from the weight of other layers.

Explanation:

1. Analyze the first option: The outer core is composed of an iron - nickel alloy. High temperatures in the outer core (around 4400 - 6100 °C) provide enough thermal energy to melt the iron - nickel alloy, causing it to be in a liquid state.
2. Analyze the second option: Saying the outer core has a "tarry consistency" is not a scientific explanation for its liquid state. Tarry consistency is more related to viscous, semi - solid materials, and it does not address the fundamental reason for the outer core being liquid.
3. Analyze the third option: The outer core is more dense than the mantle. The mantle is mainly composed of silicate rocks, while the outer core is an iron - nickel alloy which is denser. So this option is incorrect.
4. Analyze the fourth option: Extreme pressure generally tends to make materials more solid (like the inner core which is solid due to very high pressure). High pressure would not cause the outer core to be liquid; instead, it is the high temperature that overcomes the effect of pressure to keep the outer core liquid.

Answer:

The iron - nickel alloy melts due to hot temperatures.