2. How are a food chain and a food web different?
A. A food chain shows only one path of energy flow whereas a food web shows all the possible food chains in an ecosystem.
B. A food chain shows only one path of energy flow whereas a food web shows how much of the energy is transferred each time.
C. A food chain shows all the possible ways energy flows in an ecosystem whereas a food web shows only one path of energy flow.
D. A food chain shows how much energy is transferred in an ecosystem whereas a food web shows all the possible food chains.

The correct answer is A.

A food chain shows only one path of energy flow whereas a food web shows all the possible food chains in an ecosystem.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6