<u>Answer:</u>
<em>Theoretical density values </em>
- brass-

- bronze-

- steel-

<u>Explanation:</u>
All of these substances are<em> </em>alloys (a substance made from melting two or more substances, one of them usually being a metal). Brass is a combination of copper and zinc, bronze is mostly copper, tin and other non-metals as well and steel is majorly made up of iron and copper. These alloys have various uses and varying importance in different kinds of industries.
Answer:
atoms of 40K
Explanation:
You can use the molecular mass and the Avogadro´s number, in the following formula:

where
is the sample mass,
is the molecular mass of the KCl and IA(40K) is the isotopic abundance of 40K.
Now replacing the values, you can find:


conduction : a spoon resting in a cup of tea gets hot
convection: water warming on the stove
Radiation: The sun warming the earth