5. How many grams of Br is needed to make 1000.g of a 2.0ppm solution?

2.0 × 10⁻³ g

Explanation:

Step 1: Given data

Step 2: Calculate the mass of Br₂ required to prepare the solution

The concentration of Br₂ is 2.0 ppm, that is, there are 2.0 mg of Br₂ per kilogram of solution. The mass of Br₂ required to prepare 1.000 kg of solution is:

1.000 kg Solution × 2.0 mg Br₂/1 kg Solution = 2.0 mg

Step 3: Convert the mass to grams

We will use the conversion factor 1 g = 1000 mg.

2.0 mg × 1 g/1000 mg = 2.0 × 10⁻³ g

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answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.