How many grams are in 9.03×1023atoms of Copper (Cu)?

9.03 × 10²³ atoms of copper have a mass of 95.3 g.

We want to convert 9.03 × 10²³ atoms of copper to grams. We will need a series of conversion factors.

A conversion factor is an arithmetical multiplier for converting a quantity expressed in one set of units into an equivalent expressed in another.

The required conversion factor is Avogadro's number: there are 6.02 × 10²³ atoms in 1 mole of atoms.

9.03 × 10²³ atoms × (1 mol/6.02 × 10²³ atoms) = 1.50 mol

The required conversion factor is the molar mass of copper: 63.55 g/mol.

1.50 mol × 63.55 g/mol = 95.3 g

9.03 × 10²³ atoms of copper have a mass of 95.3 g.

Learn more about Avogadro's number here: link

Mass of Cu : 95.319 g

Given

9.03 x 10²³atoms of Copper

Required

mass of Cu

Solution

The mole is the number of particles(molecules, atoms, ions) contained in a substance  

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

Mol of Copper :

n = N/No

n = 9.03 x 10²³/6.02.10²³

n = 1.5

Mass of Copper :

= mol x Ar Cu

= 1.5 x 63,546 g/mol

= 95.319 g

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

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