Two isotopes of element X have average atomic mass of 54 amu. Which numerical setup can be used to determine the atomic mass of naturally occurring boron? 1)80% of 50X and 20% of 55
2)20% of 50X and 80% of 55X
3)50% of 50X and 50% of 55X
4)75 of 50X and 25% of 55X

Based on its chemical properties, identify the position of each chemical family on the periodic table.

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange

Calculate the number of kilojoules to warm 125 g of iron from 23.5°c to 78.0°c.