How many moles of copper (Cu) are in 65.8 g Cu? (3 points) A 01.04 mol Cu
B 0 10.9 mol Cu
C 41.7 mol Cu
D 63.5 mol Cu

Taking into account the definition of molar mass,  

In first place, the rule of three is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.

That is, what is intended with it is to find the fourth term of a proportion knowing the other three.  

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied.

To solve a direct rule of three, the following formula must be followed, being a, b and c known data and x the variable to be calculated:

a ⇒ b

c ⇒ x

So:

The direct rule of three is applied in this case, knowing that the molar mass of Cu is 63.54 , this is the amount of mass a substance contains in one mole.

So: if 63.54 grams of Cu are contained in 1 mole, 65.8 grams of Cu are contained in how many moles?

63.54 grams ⇒ 1 mole

65.8 grams ⇒ x

So:

Finally, the correct answer is option A. 1.04 moles of copper (Cu) are in 65.8 g Cu.

Learn more with this example:

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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