Answer:
Scientist use GPS satellites and movement tracers.
Explanation:
18m. It does not matter what direction the cat walked as long as it walked in a certain direction for said amount of distance
Answer:
All of us are exposed to radiation every day, from natural sources such as minerals in the ground, and man-made sources such as medical x-rays. According to the National Council on Radiation Protection and Measurements (NCRP), the average annual radiation dose per person in the U.S. is 6.2 millisieverts (620 millirem).
Explanation:
Simply look at the periodic table and fill in what you know based on the table
The number of protons = atomic number
The number of electrons, Which is the same as the atomic number for atoms.
The number of valence electrons that is given by the group that the element is in, the top number of each column in the periodic table.
Answer:
102 g Al₂O₃
Explanation:
To find the mass of Al₂O₃, you need to (1) convert grams Al to moles Al (via molar mass), then (2) convert moles Al to moles Al₂O₃ (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles Al₂O₃ to grams Al₂O₃ (via molar mass). It is important to arrange the ratios in a way that allows for the cancellation of units. The final answer should have 3 sig figs to reflect the given values.
Molar Mass (Al): 26.98 g/mol
Molar Mass (Al₂O₃): 101.96 g/mol
4 Al + 3 O₂ ---> 2 Al₂O₃
54.0 g Al 1 mole 2 moles Al₂O₃ 101.96 g
-------------- x ----------------- x ----------------------- x ---------------- = 102 g Al₂O₃
26.98 g 4 moles Al 1 mole
