Final answer:
The correct pair with the higher polarizability listed first is (a) Se²⁻, S²⁻, because the selenium ion is more polarizable due to its larger size and greater number of electrons.
Step-by-step explanation:
The question asks which pair is arranged with the particle of higher polarizability listed first. Polarizability refers to the ease with which the electron cloud around an atom or ion can be distorted, which typically increases with larger atomic or ionic size and the number of electrons. Among the given options:
- a. Se²⁻, S²⁻ - Selenium ion (Se²⁻) has more electrons and a larger radius than sulfur ion (S²⁻), which makes it more polarizable and correctly lists Se²⁻ first.
- b. I, I⁻ - The iodide ion (I⁻) is more polarizable than its neutral atom (I) here however the particle of higher polarizability (I⁻) is listed second.
- c. Mg²⁻, mg - This option incorrectly compares Mg²⁻ with elemental magnesium, mg, which is not a correct format for denoting elements and lacks an ion to compare with.
- d. Br, I - Iodine (I) is larger and has more electrons than bromine (Br), making I more polarizable, but it is listed second.
- e. none of these choices is correct - This option is incorrect because option (a) correctly lists the more polarizable particle first.
Therefore, the correct answer is (a) Se²⁻, S²⁻ as it has the particle of higher polarizability, Se²⁻, listed first.