Final answer:
Within a shell, s electrons are screened more effectively than p electrons, and p electrons are screened less effectively than d electrons.
This correct answer is a)
Step-by-step explanation:
Within a shell, s electrons are screened more effectively than p electrons, and p electrons are screened less effectively than d electrons.
This is because the s electrons are closer to the nucleus and have greater electron density near the nucleus, which allows them to shield the p electrons effectively.
On the other hand, the p electrons are further away from the nucleus and have less electron density near the nucleus, making them less effective at shielding the d electrons.
Therefore, the correct option is a) more effectively, less effectively.
This correct answer is a)