A sample of pure gold has a mass of 10.2 g. Calculate the number of moles in the sample and gold atoms in the sample.

Explanation:

molecular weight of gold = 197

converting 10.2 g into moles

no of moles = 10.2 / 197

= .0518 moles

one  mole of any element contains 6.02 x 10²³ number of atoms

.0518 moles will contain 6.02 x .0518 x 10²³ atoms of gold

= .311 x 10²³ no of atoms of gold .

= 3.11 x 10²² no of atoms of gold

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.