NEET Classification of Elements and Periodicity in Properties — Set 5

Question 1

Which element in group 15 forms a pentoxide with the highest thermal stability?

Accepted Answer

Thermal stability of group 15 pentoxides ($\ce{X2O5}$) decreases down the group due to weaker X-O bonds. $\ce{N2O5}$ is the most stable thermally, decomposing at a higher temperature than $\ce{P2O5}$, $\ce{As2O5}$, or $\ce{Sb2O5}$.

Question 2

Which element has the electronic configuration $1s^2 2s^2 2p^6 3s^2 3p^5$?

Accepted Answer

Total electrons = 17, corresponding to Cl (period 3, group 17). Others: S (16 electrons), Ar (18 electrons), P (15 electrons).

Question 3

Which element in group 1 has the highest reactivity with water?

Accepted Answer

Reactivity with water increases down group 1 due to decreasing ionization enthalpy. Cs (lowest ionization enthalpy) reacts most vigorously among Li, Na, K, and Cs.

NEET Chemistry: Classification of Elements and Periodicity in Properties — Practice Set 5

Q1. Which element in group 15 forms a pentoxide with the highest thermal stability?

Q2. Which element has the electronic configuration \(1s^2 2s^2 2p^6 3s^2 3p^5\)?

Q3. Which element in group 1 has the highest reactivity with water?

Q4. Which element in group 13 shows the maximum deviation from typical metallic character?

Q5. Which element in the second period has the highest electron affinity?

Q6. Which group 1 element has the highest ionic conductivity in its molten chloride form?

Q7. Which group 1 element has the highest flame coloration intensity due to its ionization energy?

Q8. Which element exhibits the most negative electron gain enthalpy?

Q9. Which group 2 element has the highest lattice energy in its chloride compound?

Q10. Which group 16 element forms a dioxide that exists as a linear gas at room temperature?