The two most abundant elements in earth's core are a. silicon and oxygen b. iron and magnesium c. nickel and silicon d. iron and nickel

The two most abundance elements in earth's crust are : silicon and oxygen

the most abundant element in earth's crust is oxygen: 46.6%.

It is found as silicates, carbonates, sulphates etc.

The second most abundant element in earth's crust is Silicon: 27.7%

Mainly it is found as silicates.

The third most abundant element in earth's crust is Magnesium: 8.1%

The fourth most abundant element in earth's crust is Iron:

D. iron and nickel

Explanation:

In the earth´s core the two most abundant elements that can be found are different than those that are abundant in the earth´s crust, in the core you can find almost 86% of iron and then closely followed by Silicon and Nickel with almost 15% between the two of them, scientists vary on the concentration of each, so from the options the one that makes the most sense would be Iron and another one of silicon or nickel, since the only one that combines iron and one of those is D, that should be correct.

a electronegativity decreases beacuse the size of nucleus is bigger.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them