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.

5. Consider | EN1 - EN2 | in Figure 2 for BeS. Based on Figure 1, is the bond in HBr less polar or more polar than the bond in BeS?

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

Look at the third line of the paragraph above figure 2. The greater the abosolute value of the difference between ENs of the 2 elements, the more polar is the bond between atoms of the elements. From figure 1 we can see H and Br The EN difference between these two elements should be 2.8-2.1=0.7, and from figure 2 we can see that the EN difference of BeS is 1.0, so HBr should be less polar