The model below shows a calcium atom. How many electrons are in the third energy level?
O 2
O 8
O 18
O 20
og

first energy level:1s2=2 electrons

2nd energy level:2s2 2p6=8 electrons

3rd energy level 3s2 3p6=8 electrons

B.8

Explanation:

Ca=20

K L M N

2 8 8 2

The third energy level of an atom (with atomic number 20 and above) contains 8 electrons.

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg