Earth's surface area is 5.10 × 108 km2, and its crust has a mean thickness of 35 km and mean density of 2.8 g/cm3. the two most abundant elements in the crust are oxygen (4.55 × 105 g/t) and silicon (2.72 × 105 g/t), and the two rarest non-radioactive elements are ruthenium and rhodium, each with an abundance of 1 × 10−4 g/t. what is the total mass of each of these elements in earth's crust? 1 metric ton (t) = 1,000 kg.

The total mass of oxygen is 2.28x10^7 kg, silicon = 1.36x10^7 kg, ruthenium and rhodium = 5x10^-3kg each.

Explanation:

The first thing to do is to solve the total mass of Earth. That is done by multiplying the density with surface area and thickness. The total mass is 5x10^10 kg. The rates given for each compound are equivalent to 1 metric ton. That value is multiplied by the mass of Earth to determine each compound's total mass. The answers for oxygen, silicon and the two rarest non-radioactive elements are 2.28x10^7 kg, 1.36x10^7kg, 5x10^-3, respectively.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.