1
NEET 2025
MCQ (Single Correct Answer)
+4
-1

Which of the following are paramagnetic?

A. $\left[\mathrm{NiCl}_4\right]^{2-}$

B. $\mathrm{Ni}(\mathrm{CO})_4$

C. $\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$

D. $\left[\mathrm{Ni}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$

E. $\mathrm{Ni}\left(\mathrm{PPh}_3\right)_4$

Choose the correct answer from the options given below :

A
A and D only
B
A, D and E only
C
A and C only
D
B and E only
2
NEET 2025
MCQ (Single Correct Answer)
+4
-1

If the half-life ( $t_{1 / 2}$ ) for a first order reaction is 1 minute, then the time required for $99.9 \%$ completion of the reaction is closest to :

A
5 minutes
B
10 minutes
C
2 minutes
D
4 minutes
3
NEET 2025
MCQ (Single Correct Answer)
+4
-1

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

A
$$\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-19.62 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-8.72 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}$$
B
$$\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned}$$
C
$$\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-19.62 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-8.72 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}$$
D
$$\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=26.4 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned}$$
4
NEET 2025
MCQ (Single Correct Answer)
+4
-1

Among the given compounds I-III, the correct order of bond dissociation energy of C-H bond marked with * is :

NEET 2025 Chemistry - Some Basic Concepts of Organic Chemistry Question 2 English

A
III $>$ II $>$ I
B
II $>$ III $>$ I
C
II $>$ I $>$ III
D
I $>$ II $>$ III
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