Taylor was thirsty and decided to mix up a pitcher of lemonade. she put lemon juice, water, and sugar into a pitcher and stirred it to create this wonderful new drink. how could taylor decide if she just created a mixture or a compound?

Answer is: it must be a mixture as she can separate all of the individual ingredients.

Pure substance is made of only one type of atom (element) or only one type of molecule (compound), mixtures and solutions are made from two or more types of pure substances.  

Elements (for example copper, iron, sulfur) and compounds (water, sodium chloride) have definite and constant composition with distinct chemical properties.  

Pure substances can be separated chemically, not physically, that is difference between pure substances and mixtures.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year