Exhibits Use the information to answer the following question.
Students are trying to calculate the heat of reaction for the following
target reaction.
A + 3B 3C + 2D
They find the heat of reactions for the two reactions as shown.
A + 2B - C + D AH= -20 kJ
B - 2C + D
AH= -45 kJ
When the students used Hess's Law correctly, what is the heat of
reaction for the target reaction?
O A. -65 kJ
OB. +65 kJ
C. -25 kJ
D. +25 kJ

Noble gases are the most reactive elements on the periodic table. a. true b. false

Which traits do human embryos have that link them to a common ancestor with fish and reptiles? a. scales and tail b. gill slits and scales c. tail and gill slits d. hair and tail

Nconcentration refers to the molar concentration of an ion in solution. it may be identical to, or greater or less than, the molar concentration of the compound containing the ion that was used to make the solution. for soluble salts, the molarity of a particular ion is equal to the molarity of that compound times the subscript for that ion. for example, 1 m of alcl3 is 1 m in al3+ and 3 m in cl−. 1 m of (nh4)2so4 is 2 m in nh4+ and 1 m in so42−. part a what is the concentration of k+ in 0.15 m of k2s? view available hint(s) nothing m m part b if cacl2 is dissolved in water, what can be said about the concentration of the ca2+ ion? view available hint(s) if is dissolved in water, what can be said about the concentration of the ion? it has the same concentration as the cl− ion. its concentration is half that of the cl− ion. its concentration is twice that of the cl− ion. its concentration is one-third that of the cl− ion. part c a scientist wants to make a solution of tribasic sodium phosphate, na3po4, for a laboratory experiment. how many grams of na3po4 will be needed to produce 550 ml of a solution that has a concentration of na+ ions of 0.700 m ? express your answer numerically in grams. view available hint(s) mass of na3po4 n a 3 p o 4 = nothing g provide feedback