The answer is B i know this because i just took it
Answer: 1and 4
Explanation: iron is an element not an alloy. An ionic lattice is not bonded covalently.
Hydrogen only has 1 electron so not A.
Barium has 2 valence electrons so answers B!
Answer:
enables us to understand those changes which no human being has ever seen (or if they have, they didn't record it) and to relate them to modern changes.
Expl
