Browse Questions

Which of the following statements regarding Halogens is NOT correct?

(1) The energy difference between ground state and first excited state increases on descending the Group 17

(2) I$_2$ conducts electicity to a small extent due to its self ionization 3I$_2 \leftrightharpoons$ I$_3$$^+$ + I$_3^{\text{-}}$

(3) Conductivity of I$_2$ increases on increasing temperature

(4) The compounds C$_n$ F$_{2n+2}$ are known as perfluoro componds

$\begin{array}{1 1} (A) (2) and (3) \\ (B) Only (3) \\(C) Only (1) \\ (D) Only (4)\end{array}$

Answer: (1) The energy difference between ground state and first excited state increases on descending the Group 17.
The energy levels become closer. The promotional energy between ground to first decreases and the wavelength of energy becomes larger. This is supported by the colour of halogens.