Sample Chemistry Placement Exam Questions with Certified Answers

Sample Chemistry Placement Exam Questions with Certified Answers Answer: Oxygen Aluminum forms a +3 ion. In order for the formula unit Al2X3 to be electrically neutral, the element X must form a -2 ion. Nonmetals in the oxygen column do this. Of these elements, only oxygen is a diatomic gas. Aluminum reacts with element X to form a compound with the formula A2X3. Element X exists as diatomic molecules, X2, in the gaseous state at normal temperature and pressure. Element X must be? Answer: 5 The balanced equation is 2 C2H4O + 5 O2 → 4 CO2 + 4 H2O What is the coefficient of O2 when the following equation is balanced? C2H4O + O2 → CO2 + H2O Answer: 2.00 8.00 mol GeF3H ( 1 mol GeH4/ 4 mol GeF3H) = 2.00 mol GeH4 How many moles of GeH4 are needed to form 8.00 moles of GeF3H according to the following reaction? GeH4 + GeF4 → 4 GeF3H Answer: A nonmetal Nonmetals are toward the upper right of the periodic table. All the elements in the fluorine column are nonmetals. According to its location in the periodic table, the element bromine (element # 35) is best described as Answer: NaCl HCl, hydrochloric acid, is a strong acid. NH3, ammonia, is a weak base. In a solution of NaHCO3, sodium hydrogen carbonate (baking soda), the hydrogen carbonate ion, HCO3- , acts as a base. Neither the sodium ion Na+, nor the chloride ion, Cl - , which form when NaCl is dissolved in water, has significant acidic or basic properties. Which of the following species is neither acidic nor basic when dissolved in water Answer: 8.3 x 108 The "calculator answer" is 8.2695.... x 108. When the numbers in the numerator are subtracted the result, 8.53, must be rounded to one decimal place,