How are the atomic masses that are listed on the periodic table determined?

The astronomical unit (au) is a unit of distance used in astronomy and is equivalent to the mean distance between Earth and the sun. One au is equal to 1.496 ×1011m. The closest Pluto and Earth get to each other during their orbits is approximately 28 au. How many kilometers is the distance between Earth and Pluto at this point?

Solve the following problem and round the answer to the correct number of significant digits.  

Elemental chlorine, Cl2, is a gas that has corrosive chemical properties. Select an element that is likely to have similar chemical properties.

Select the element that the chemical symbol W represents.

Approximate the atomic mass of a fictional element X with the following isotope data. ​ Isotope Abundance 45X 75.0% 47X 25.0% ​

Select the correct sequence of events in the scientific method.

A 151 g sample of lead has a volume of 13.4 mL. Calculate the density of lead.

You DO NOT need to rewrite the questions on your paper. You can just number each answer with work as appropriate. For the sketching of the graph, you may use graph paper, or you may use regular paper and label all key points/asymptotes.  MATH&142OL Test 2 W25.pdf

Which of the following marketed by target electronic communications?