Question

39) What property of liquids explains the formation of leaves? A) surface tension B) adhesion C) viscosity D) vapor pressure E) None of the choices are correct. mation of spherical water droplets on green 3 9) - um at constant pressure and temperature has the volume 40) 40) A balloon containing helium at constant pres doubled by adding a more helium. Which ' adding a more helium. Which statement(s) isare) TRUE? A) The number of moles of helium doubled. B) The number of helium atoms doubled. C) The mass of helium in the balloon doubled. D) All of the statements are true. E) All of the statements are false. 41) Hydrogen cyanide (HCN) is a poisonous gas tha 41) the gas chamber. How many moles of HCN N) is a poisonous gas that has been used to execute prisoners in nber. How many moles of HCN are present in a 67.0 L cylinder at 25.0°C that is registering a pressure of 742 mm Hg? A) 2.24 mol B) 2.81 mol C) 2.67 mol D) 1.71 x 103 mol E) 31.9 mol barnical equation 42) 42) Iron reacts with oxygen to form iron(III)oxide according to the chemical equation below. What is the theoretical vield of product when 5.00 grams of Fe react with excess O2? [Molar masses: Fe, 55.85 g/mol; 0, 16.00 g/mol] 4Fe(s) + 302(8) A) 6.53 g 2Fe2O3(s) B) 7.15 g C) 13.1 g D) 2.50 g E) 70.5 g 43) How is the reaction shown below best classified? 43) 2HgO(5) 2Hg() + O2(g) A) combustion B) double-replacement C) combination D) decomposition E) single-replacement shine na AMP

Answer 1

(39) Surface tension is a property surface of a water which allows to resist an external force acting on it. It explains about the formation of spherical shape of water dropletes. Therefore, the correct option is A ------------------ (40) Euation of state is PV = nRT here, Pis pressure, T' is temperature, V is volume, nis number of moles of gas and Ris gas constant Given pressure and temperature are constant. Volume is doubles so that the number of moles of gas are doubled. As the moles are doubled, mass of the gas also doubles Therefore, the correct option is D - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (41) Equation fo state is PV = nRT Volume, V = 67.0 L Temperature, T = 25 °C = 273 + 25 K = 298 K gas constant, R= 62.36367 L mmHg/mol K Pressure, P = 742 mm Hg Calculate the moles as follows: PD RT 742 mm Hg 67.0L 62.36367 L mm Hg/molK x 298 K = 2.67 mol Therefore, the correct option is c.

(42) Write the reaction as follows: 4Fe(s) +30,(8) ► 2Fe,0, (s) mass of Fe = 5.00 g molar mass of Fe = 55.85 g/mol mass of Fe 5.00 g moles of Fe = molar mass of Fe 55.85 g/mol 0.0895 mol From the reaction, moles of Fe_moles of Fe, moles of Fe,0,= 2 moles of Fe moles of rº344 = 0.04475 mol molar mass of Fe,O3 = 159.7 g/mol mass of Fe2O3 = molar mass of Fe,0, xmoles of Fe,93 = 159.7 g/mol 0.04475 mol = 7.15g Therefore, the correct option is B