Question

19) Iron is produced from its one by the reactions 2 C O 2 Fe:O ) CO 2 es 3COAR) How many moles of Ol) are needed to produce 1 mole of Fe(s)? a) 1/2 mole o 1/4 moto 1 mole O d) 3/2 moleo 20) Iron (1) sulfate reacts with potassium hydroxide in aqueous solution to form a precipitate. The net lonic equation for this reaction is: a) Fel. 50. Feso, 2 50, SO. c)Fe +20 Feco ). d) F K 21) Hydrochloric acid reacts with magnesium metal. What is the net lonic equation for this reaction a) 2H" (aq) +2CH(aq) + Mg(s) H(s) Mecl, b) 2 (aq) + Mg(s) -H ) M (ac) c) 2 CH(aq) + Mg(s) Cl ) + Mg(aq) d) 2 (aq) + Mg M C , (s) e) 2 HCl(aq) + Mg(s) + Mg (s) + 2 H (aq) 22) Copper reacts with silver nitrate solution to form silver metal and copper (I) nitrate solution. If 5.25 g of Cu is reacted with 6.25 ml of 0.500 MAENO, solution, how much silver is produced in the reaction? a) 5.25 g b) 337 c) 8.918 d) 1.05 g e) 0.337 23) A student prepared 250 L of a 0.535 M solution of sodium chloride from 405.3 ml of a stock solution. What is the molarity of the stock solution? a) 3.30 M b) 86.7 M c 0.0867 M d ) 0.0033 M e ) 6.60 M 24) A 20.Og sample of HF is dissolved in water to give 200 mL of solution. The concentration of the solution is: a) 1.0 M b ) 3.0 M c 0.10 M d) 5.0Me ) 100M 25) What volume of 0.750 M NH, in liters, would you use to prepare 0.500 L of 0.250M NH, solution? a) 0.167L b) 1.50L C ) 6.00L d) 0.500L e) 0.250 L 26) A certain solid substance which is very hard, has a high melting point and is non-conducting unless melted is most likely to be: a) b b) NaCI C CO, d) H0 e) Cu 27) What is the minimum wavelength of a photon of light that can excite an electron in the hydrogen atom from the n.1 to the n = 8 energy level a) 92.7 nm b) 122 nm c) 40.1 m d ) 60.4 nm e) 300 m a) b) c) d) s 28) Which of the following atoms or lons has 3 UNPAIRED electrons? e) Zn a) O b ) 3 C) 5 29) How many forbitals have n=3? d) 7 e) 1 30) An element with the electron configuration [Xe] 65 4745d would belong to which class of elements? a) transition elements b) alkaline earths c) halogens d) rare earth elements e) none of the above 31) of the following elements, which has the lowest first ionization energy? a) ab) Ba c) si d) Pe) a 32) The isotopes of an element have the same: a) mass number b) number of neutrons c) "A" number d) "Z" number 33) A 1.00 sample of NH.NO, is decomposed in a bomb calorimeter. The heat capacity of the system is 1.23 kJ kal. The temperature increases by 6.12 K. What is the molar heat of decomposition for ammonium nitrate? a) 602 kJ/mol b) -398 kl/mol C 7.53 kJ/mol d) 164 kl/mol

Answer 1

19) We have, 2 C(s) + O2(g) → 2 CO (g) 2 mol 1 mol 2 mol Fe2O3 (s) + 3 CO (g) → Fe (s) + 3 CO2 (g) 1 mol 3 mol 2 mol 3 mol Calculate the necessary moles of CO to produce 1 mol of Fe 3 mol CO 3 moles CO = 1 mol Fex 2 mol Fe, mol Co Calculate the necessary moles of O2 to produce 1 mol of Fe 1 mol 02 3 moles 02 = 2 mol co4 Correct answer b. Ox = molo

20) Write the balanced molecular reaction FeSO4 (aq) + 2KOH (aq) → K2SO4 (ag) + Fe(OH)2 (s) Write the total ionic equation and cancel the ions that are in both side of the reaction Remember, Fe(OH)2 is insoluble so that it is not completely dissociated FeSO4 and K2SO4 are soluble so that they are completely dissociated KOH is a strong base so that, it is completely dissociated Fe+2 (ag) + S0=2(aq) + 2K+ (aq) + 2OH- (aq) + 2K+ (aq) +50-2 (aq) + Fe(OH)2 (s) Write the net ionic equation Fe+ (aq) + 20H- (aq) → Fe(OH)2 (3) Correct answer c.