What is the main difference between the outer core and the inner core of the Earth?

Question

The inner core is cooler because it's solid and the outer core is hotter and liquid.

The inner core is solid iron and nickel and the outer core is liquid iron and nickel.

The inner core is mostly solid iron, the outer core is mostly liquid nickel.

The inner core is hotter and liquid and the outer core is cooler and solid.

Answer 1

The main difference between the outer core and the inner core of the Earth is that the inner core is solid and primarily composed of iron and nickel, while the outer core is liquid and also mostly composed of iron and nickel. Therefore, the correct statement is:

The inner core is solid iron and nickel and the outer core is liquid iron and nickel.