Question

Which of the following statements is not true for halogens?
A. All form monobasic oxyacids.
B. All but fluorine show positive oxidation states.
C. All are oxidizing agents.
D. Chlorine has the highest electron-gain enthalpy.

Answer 1

Hint: Halogens are the group of elements located in p-block and have high electronegativity values when compared to remaining periodic table elements. Because of the high electronegativity value halogens accept electrons easily.

Complete answer:
- In the question, it is asked which statement is not true among the given options.
- Coming to option A, All form monobasic oxyacids.
- We know that fluorine shows only a +1 oxidation state but other halogens show both positive and negative oxidation states. Because of the small size, high electronegativity fluorine forms only one oxy acid (HOF), Therefore statement A is incorrect.
Coming to option B, All but fluorine show positive oxidation states.
Yes, it's true, all halogens show positive oxidation states, so option B is correct.
- Coming to option C, All are oxidizing agents.
- All halogens have high electronegativity values so they accept electrons and act as good oxidizing agents too. So option C is also correct.
- Coming to option D, Chlorine has the highest electron-gain enthalpy.
Chlorine has less electronegative value when compared to fluorine but has high electron gain enthalpy due to available d-orbitals. So, the correct answer is “Option D”.

Note: The fluorine has less size but high electronegative value. Due to the smaller size, the electron gain enthalpy of fluorine is less when compared to electron gain enthalpy of chlorine even though less electronegative value when compared to fluorine