1
JEE Main 2026 (Online) 2nd April Evening Shift
Numerical
+4
-1
Change Language

Number of paramagnetic ions among the following d- and f-block metal ions is __________.

Mn2+, Cu2+, Zn2+, Yb2+, Sc3+, La3+, Gd3+, Lu3+, Ti4+, Ce4+

(Atomic number of Mn = 25, Cu = 29, Zn = 30, Yb = 70, Sc = 21, La = 57, Gd = 64, Lu = 71, Ti = 22, Ce = 58)

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2
JEE Main 2026 (Online) 22nd January Evening Shift
Numerical
+4
-1
Change Language

Among the following oxides of $3 d$ elements, the number of mixed oxides are $\_\_\_\_$ .

$$ \mathrm{Ti}_2 \mathrm{O}_3, \mathrm{~V}_2 \mathrm{O}_4, \mathrm{Cr}_2 \mathrm{O}_3, \mathrm{Mn}_3 \mathrm{O}_4, \mathrm{Fe}_3 \mathrm{O}_4, \mathrm{Fe}_2 \mathrm{O}_3, \mathrm{Co}_3 \mathrm{O}_4 $$

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3
JEE Main 2026 (Online) 21st January Morning Shift
Numerical
+4
-1
Change Language

Consider the following reactions :

$$ \begin{aligned} & \mathrm{NaCl}+\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{~A}+\mathrm{KHSO}_4+\mathrm{NaHSO}_4+\mathrm{H}_2 \mathrm{O} \\ & \mathrm{~A}+\mathrm{NaOH} \rightarrow \mathrm{~B}+\mathrm{NaCl}+\mathrm{H}_2 \mathrm{O} \\ & \mathrm{~B}+\mathrm{H}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O}_2 \rightarrow \mathrm{C}+\mathrm{Na}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O} \end{aligned} $$

In the product ' $C^{\prime}$, ' $X$ ' is the number of $O_2^{2-}$ units, ' $Y$ ' is the total number oxygen atoms present and ' $Z$ ' is the oxidation state of $C r$. The value of $X+Y+Z$ is $\_\_\_\_$ .

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4
JEE Main 2025 (Online) 3rd April Evening Shift
Numerical
+4
-1
Change Language
Among, $\mathrm{Sc}, \mathrm{Mn}, \mathrm{Co}$ and Cu , identify the element with highest enthalpy of atomisation. The spin only magnetic moment value of that element in its +2 oxidation state is__________BM (in nearest integer).
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