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Energy and radius of first Bohr orbit of He^+and Li^2+ are [Given R_ H=2.18 × 10^-18 ~J, a_0=52.9 pm ]

NEET UG 2025 — Chemistry Physical Chemistry

2025mcqmedium

Energy and radius of first Bohr orbit of He+\mathrm{He}^{+}He+and Li2+\mathrm{Li}^{2+}Li2+ are [Given RH=2.18×10−18 J,a0=52.9pm\mathrm{R}_{\mathrm{H}}=2.18 \times 10^{-18} \mathrm{~J}, \mathrm{a}_0=52.9 \mathrm{pm}RH​=2.18×10−18 J,a0​=52.9pm ]

Official previous-year question

Held on 30 Apr 2025 · Verified 9 Jul 2026.

Options

  1. A

    En(Li2+)=−19.62×10−18 J;rn(Li2+)=17.6pmEn(He+)=−8.72×10−18 J;rn(He+)=26.4pm\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-19.62 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-8.72 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}​En​(Li2+)=−19.62×10−18 J;rn​(Li2+)=17.6pmEn​(He+)=−8.72×10−18 J;rn​(He+)=26.4pm​

  2. B

    En(Li2+)=−8.72×10−18 Jrn(Li2+)=26.4pmEn(He+)=−19.62×10−18 J;rn(He+)=17.6pm\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-18} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=26.4 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned}​En​(Li2+)=−8.72×10−18 Jrn​(Li2+)=26.4pmEn​(He+)=−19.62×10−18 J;rn​(He+)=17.6pm​

  3. C

    En(Li2+)=−19.62×10−16 Jrn(Li2+)=17.6pmEn(He+)=−8.72×10−16 Jrn(He+)=26.4pm\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-19.62 \times 10^{-16} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-8.72 \times 10^{-16} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}​En​(Li2+)=−19.62×10−16 Jrn​(Li2+)=17.6pmEn​(He+)=−8.72×10−16 Jrn​(He+)=26.4pm​

  4. D

    En(Li2+)=−8.72×10−16 Jrn(Li2+)=17.6pmEn(He+)=−19.62×10−16 J;rn(He+)=17.6pm\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-16} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned}​En​(Li2+)=−8.72×10−16 Jrn​(Li2+)=17.6pmEn​(He+)=−19.62×10−16 J;rn​(He+)=17.6pm​

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