An old (pre-1987) penny is nearly pure copper. if such a penny has a mass of 3.3 g, how many moles of copper atoms would be on one penny?

Approximately 3.1 × 10²².

Explanation:

Start by considering: how many moles of copper atoms in this 3.3-gram coin?

To answer that, it would be necessary to know the mass of one mole of copper atoms. The mass (in grams) of one mole of copper atoms is numerically equal to the relative atomic mass of copper. Look up the relative atomic mass of copper on a modern periodic table.

Cu: 63.546.

In other words, the mass of one mole of copper atoms is equal to 63.546 grams. Hence, the number of moles of copper atoms in the 3.3-gram coin would be equal to

.

How many copper atoms would that be? Avogadro's Constant gives the number of particles in one mole.

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Since there are approximately copper atoms, the number of copper atoms would be

.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic