WB JEE 2026

Density and volume of a body are given as $(20 \pm 4) \mathrm{gm} / \mathrm{cm}^3$ and $(10 \pm 1) \mathrm{cm}^3$ respectively. The absolute error in measurement of mass is

The plot of radial probability density（ $4 \pi r^2 R^2$ ）against $r$ for an electron in $n p$ orbital of a many electron atom is given below．

The value of $n$ is

Let $A_1, A_2, \ldots, A_6$ are six sets, each with four elements and $B_1, B_2, \ldots ., B_n$ are $n$ sets, each with two elements. Let $S=A_1 \cup A_2 \cup \ldots \cup A_6=B_1 \cup B_2 \cup \ldots \cup B_n$.

Given that each element of $S$ belongs to exactly four of the A's and to exactly three of the B's. Then $n$ is

Which of the velocity-time $(v-t)$ graph(s) can possibly represent one-dimensional motion of a particle?

The mass of an electron is $9 \cdot 1 \times 10^{-31} \mathrm{~kg}$ ．If its K ．E．is $3 \cdot 0 \times 10^{-25} \mathrm{~J}$ ，its wavelength is（approximately）

On the set $\mathbb{R}$ of real numbers the relation $\rho$, defined by $\mathrm{x} \rho \mathrm{y}(\mathrm{x}, \mathrm{y} \in \mathbb{R})$ iff