How does the author develop the central idea that the periodic table reflects the similarities between chemical elements?
by describing how other scientists responded to the theory
originated by Mendeleev
by detailing the challenges that Mendeleev faced in creating the
periodic table
y
by explaining the card game Mendeleev designed to arrange
elements by their atomic masses
by expressing the diligence that Mendeleev displayed in his
efforts to create the periodic table

hancock was president of congress when the declaration of independence was adopted and signed. he is primarily remembered by americans for his large, flamboyant signature on the declaration, so much so that "john hancock" became, in the united states, an informal synonym for signature.

explanation:

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."

b is the correct answer

to convince americans of the importance of others.