Which situation is a result of human activities a. decay of leaves in a forest adds to soil fertility b. acid rain in an area kills fish in a lake c. ecological succession following volcanic activity reestablishes an ecosystem. d. natural selection on an island changes gene frequencies

Given the table below, what is the chemical formula for a compound between rb and the nitrate ion no3 -1? nitrate ion no3 -1 phosphate po4 -3 sulfate so4 -2 acetate c2h3o2 -1 ammonium nh4 +1 chromate cro4 -2 carbonate co3 -2 dichromate cr2o7 -2 permanganate mno4 -1 sulfite so3 -2 rbno3 rb2no3 rb(no3)2 rb2(no3)3

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false

Consider the following reaction at equilibrium: c(s)+h2o(g)⇌co(g)+h2(g) predict whether the reaction will shift left, shift right, or remain unchanged upon each of the following disturbances. a) c is added to the reaction mixture. b) h2ois condensed and removed from the reaction mixture c) co is added to the reaction mixture d) h2 is removed from the reaction mixture.