The inner core consist of only iron and nickel and it is so hot (9,000 degrees F.) that it gets hardened, however the outer core is liquid iron and nickel because cannot harden because there is too much pressure. Hope it helps! Merry Christmas!!!
Answer: Even though there are smalll amounts of these gases, they can have a major effect on Earth. For example, increased amounts of carbon dioxide are having a major effect on global warming. :)