Read the following statements carefully: (I) Atomic radius strictly decreases from left to right across the entire second period. (II) A cation is always smaller than its parent atom. (III) An anion is always larger than its parent atom. (IV) Among isoelectronic species, the ionic radius increases with an increase in nuclear charge. How many of the above statements are correct?

Step-by-step solution

Let us evaluate each statement based on periodic trends: Statement (I) is incorrect. While atomic radius generally decreases across a period due to increasing effective nuclear charge, noble gases at the end of the period (like Neon) are an exception. Their non-bonded (van der Waals) radii are measured, which are significantly larger than the covalent radii of the preceding halogens. Statement (II) is correct. A cation is formed by the loss of electrons, which increases the effective nuclear charge per electron, pu