An extinction coefficient for double stranded dna is 0.02 ｵl/[ng*cm]). which preparation would you be comfortable using the 260nm absorbance and this extinction coefficient to calculate the concentration of dna from? what is that concentration in ｵg/ml? why would you be uncomfortable calculating a concentration for the other sample?

Elements and compounds are pure substances that cannot be broken down physically into a simpler substance. a physical change doesn’t break the bonds between atoms of a substance or form new ones. compounds can be broken down by a chemical change. a chemical change breaks chemical bonds and/or forms new ones between atoms of a substance. what simple substance would a compound break into? the basic elements that make it up! for example, if you passed a very strong electric current through water you’d break the chemical bonds in water and be left with oxygen and hydrogen. which of the following is an example of a chemical change? a separating water into different glasses b breaking frozen ice cubes with a hammer c running an electric current through water d boiling water to evaporate it on a stove

The frequency of alleles in a population that is in hardy weinberg equilibrium? a . changes in each successive generation b. is less important than the frequency genotypes c. shows evidence of the process of natural selection d. remains the same over several generations

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.