On the basis if above passage, answer the questions

When tow different halogens react with each other, interhalogen compounds are formed. They can be assigned general compositions as \(XX'\), \(XX'_3\), \(XX'_5\); and \(XX'_7\), where \(X'\) is a halogen of larger size and \(X\) of smaller size and X is more electropositive than X increases, the number of atoms per molecule also increases.

In interhalogemns \(XX'_7\), what are \(X\) and \(X'\) respectively?

Iodine and fluorine

The correct answer is option 2. Iodine and fluorine.

Interhalogen compounds are formed when two different halogen atoms combine. In the compound \( XX'_7 \), the subscripts \( 7 \) indicate that there are seven atoms of the more electronegative halogen (\( X' \)) surrounding one atom of the less electronegative halogen (\( X \)).

Given that \( X \) comes before \( X' \) in the compound's formula, it suggests that \( X \) is less electronegative than \( X' \). In the periodic table, electronegativity generally increases from left to right and from bottom to top. Fluorine is the most electronegative element, followed by chlorine, bromine, and iodine.

So, for \( XX'_7 \), \( X \) would likely be iodine, and \( X' \) would be fluorine. This pairing aligns with the fact that iodine is less electronegative than fluorine.

Therefore, the correct option is indeed 2. Iodine and fluorine.