Passage I

Figure 1 is a simplified periodic table that gives the atomic number, symbol, name, and electronegativity (EN) of 21 elements. Rows of elements are called periods. Columns of elements are called groups.

Figure 1 adapted from Nivaldo J. Tro, Chemistry: A Molecular Approach, 2nd ed.©2011 by Pearson Education, Inc.

The greater the EN of an element, the more strongly an atom of that element attracts electrons to itself in a chemical bond. The greater the absolute value of the differ­ence between the ENs of 2 elements, | EN1 - EN2 |, the more polar is the bond between atoms of the elements. Figure 2 gives, for each of 6 compounds, | EN1 - EN2 | and the bond energy at 298 K (the energy needed to break all the bonds in 1 mole of a compound at 298 K).

Figure 2 adapted from James G. Speight, Lange's Handbook of Chemistry, 16th ed. ©2005 by McGraw-Hill, Inc.

6. Consider a sample composed of molecules of HI. Based on Figure 2, at 298 K, would the amount of energy required to break all the bonds in this sample be greater than 300 kJ or less than 300 kJ ?

Answer and Explanation

Your Answer is

Correct Answer is J

Explanation

Pay attention to the * mark 1 mole=6×1023 molecules under figure 2, and the 3×1023 given in the title is only a half mole, so at this time The bone energy should be less than the value given in figure 2