NEET Classification of Elements and Periodicity in Properties — Set 15

Question 1

Which of the following elements has the lowest melting point?

Accepted Answer

Melting point decreases down group 1 due to weaker metallic bonding. Cs (group 1, period 6) has the lowest melting point among Li, Na, and Cs.

Question 2

Which element has the ground state electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2$?

Accepted Answer

This configuration (Z=28) corresponds to Ni (period 4, group 10), with $3d^8 4s^2$, distinguishing it from Fe ($3d^6 4s^2$), Co ($3d^7 4s^2$), or Cu ($3d^{10} 4s^1$).

Question 3

Which ion among the following isoelectronic species with 36 electrons has the highest lattice energy when paired with $\ce{F^-}$?

Accepted Answer

For isoelectronic species (36 electrons), lattice energy increases with charge. $\ce{Sc^3+}$ (Z=21, +3) forms $\ce{ScF3}$ with the highest lattice energy compared to $\ce{K+}$, $\ce{Ca^2+}$, or $\ce{Br^-}$.

NEET Chemistry: Classification of Elements and Periodicity in Properties — Practice Set 15

Q1. Which of the following elements has the lowest melting point?

Q2. Which element has the ground state electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2\)?

Q3. Which ion among the following isoelectronic species with 36 electrons has the highest lattice energy when paired with \(\ce{F^-}\)?

Q4. Arrange F, Cl, Br in order of decreasing electron gain enthalpy (most negative to least negative).

Q5. Which element in group 16 has the highest tendency to exhibit a +6 oxidation state?

Q6. Which d-block element in period 5 has the highest electronegativity?

Q7. Which oxide of a group 17 element is the most stable in its highest oxidation state?

Q8. Which element has the ground state electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^1\)?

Q9. Which element has the highest first ionization enthalpy among group 13 elements?

Q10. Which group 15 element exhibits the maximum oxidation state of +5 in its compounds?