Question

The following statements concern elements in the periodic table. Which of the following is true ?

• A. All the elements in Group 17 are gases.
• B. The Group 13 elements are all metals.
• C. Elements of Group 16 have lower ionization enthalpy values compared to those of Group 15 in the corresponding periods.
• D. For Group 15 elements, the stability of +5 oxidation state increases down the group.

Answer 1

The Correct Option is C

To determine which of the given statements about elements in the periodic table is true, let's analyze each statement one by one:

1. All the elements in Group 17 are gases:
   Group 17 is known as the halogens which include elements like fluorine, chlorine, bromine, iodine, and astatine. Only fluorine and chlorine are gases at room temperature. Bromine is a liquid, while iodine and astatine are solids. Therefore, this statement is false.
2. The Group 13 elements are all metals:
   Group 13, also known as the boron group, includes the elements boron, aluminum, gallium, indium, and thallium. While most are metals, boron is a metalloid. Hence, this statement is false.
3. Elements of Group 16 have lower ionization enthalpy values compared to those of Group 15 in the corresponding periods:
   The ionization enthalpy generally decreases down a group and across a period from left to right. Group 15 elements (like nitrogen, phosphorus) have relatively higher ionization enthalpies due to their half-filled p orbitals, which are more stable. Group 16 elements, such as oxygen and sulfur, have lower ionization enthalpies compared to their Group 15 counterparts in the same period. Therefore, this statement is true.
4. For Group 15 elements, the stability of +5 oxidation state increases down the group:
   The stability of higher oxidation states (+5) generally decreases down the group due to the inert pair effect, which becomes more significant. Elements like nitrogen exhibit a +5 oxidation state more readily, whereas bismuth is more stable in the +3 oxidation state. Therefore, this statement is false.

Based on this analysis, the correct statement is: "Elements of Group 16 have lower ionization enthalpy values compared to those of Group 15 in the corresponding periods."