#1: Which of the following is an exothermic reaction? A. dissolving ammonium nitrate in water to cool the water B. condensation C. melting ice D. dissolving sugar in water. #2: Two objects (A and B) of the same temperature are in contact with each other. Which of the following statements is true? A. Heat transfers from object B to object A, because molecules from B collide with those from A. B. Heat transfers from object A to object B, because molecules from A collide with those from B. C. Although the molecules collide, no heat transfers because there is no temperature difference between the objects. D. No heat transfers, because there are no collisions between the molecules of the objects. #3: Which of the following parameters is kept constant in a coffee-cup calorimeter? A. temperature B. volume C. pressure D. kinetic energy #4: What type of substance would be best for use in a heating system? A. a liquid with a high specific heat B. a solid with a high specific heat C. a liquid with a low specific heat D. a gas with a low specific heat. #5: The reaction 2 NO(g) → N2(g) + O2(g) has a ΔH = -180.5 kJ. How much heat will be required to produce 44.8 L of NO by the reverse reaction? A. 644 kJ B. 180.5 kJ C. 301 kJ D. 322.3 kJ

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Hagrid
These are the following answers to the five questions:
(1) (B) condensation. Condensation is exothermic, but it's not a reaction, it's a physical change. 
(2) (C) Although the molecules collide, no heat transfers because there is no temperature difference between the objects. 
(3) (C) pressure
(4) (A) a liquid with a high specific heat
(5) Supposing the NO is measured at STP: 
(44.8 L) / (22.4 L/mol) x (180.5 kJ / 2 mol NO) = (B) 180.5 J 

(1) (B) condensation. Condensation is exothermic, but it's not a reaction, it's a physical change. 

(2) (C) Although the molecules collide, no heat transfers because there is no temperature difference between the objects. 

(3) (C) pressure

(4) (A) a liquid with a high specific heat

(5) Supposing the NO is measured at STP: 

(44.8 L) / (22.4 L/mol) x (180.5 kJ / 2 mol NO) = (B) 180.5 J