22. a
Answer the following questions with reference to group VII A elements (or halogens).
Name and arrange the elements in order of increasing electronegativity.
Name the radio-active element in this group.
Astatine
Which is the most powerful oxidising agent?
liv)
Name four halogen acids.
State which is the strongest acid mentioned in (iv).
Answers
Answer:
1) Order of Increasing Electronegativity of Halogens IODINE<BROMINE<CHLORINE<FLUORINE
2)Radioactive Element: ASTATINE
3) F2{FLUORINE} is the most powerful oxidising agent among Halogens
4) Hydrogen Halides[HF, HCL, HBR, HI] are examples of Halogen Acids and the strongest is [HI] HydrogenIodide(Hydriodic Acid)
Explanation:
1) It decreases on moving down the group because size of atom increases. Decreasing order of electro-negativity of halogens is F, Cl, Br, I. Fluorine has highest electronegativity among all the known elements.
2) Although astatine is radioactive and only has short-lived isotopes, it behaves similar to iodine and is often included in the halogen group.
3)Among halogens, fluorine is the strongest oxidising agent. It has highest value of oxidation potential. It is due to its low heat of dissociation and high heat of hydration which have more than compensated the lower value of electron affinity.
4)The order of acidic character can be explained in terms of strength of H−X bonds, which is in the orderH−I<H−Br<H−Cl<H−F.Since H−I bond is weakest, therefore, HI is the strongest acid. On the other hand H-F bond is strongest, hence it is the weakest acid among all the halogen acids.