Question
In which of the following decay, the element does not change
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Which of the following statement($s$) is(are) correct in SI units?
$(A)$ When $x=q$, the magnitude of the electric field at $O$ is zero.
$(B)$ When $x=-q$, the magnitude of the electric field at $O$ is $\frac{q}{6 \pi \in_0 a^2}$.
$(C)$ When $x=2 q$, the potential at $O$ is $\frac{7 q}{4 \sqrt{3} \pi \in_0 a}$.
$(D)$ When $x=-3 q$, the potential at $O$ is $\frac{3 q}{4 \sqrt{3} \pi \in_0 a}$.
| Column - $\mathrm{I}$ | Column - $\mathrm{II}$ |
| $(a)$ Viscous force | $(i)$ $\left[ {{M^1}{L^1}{T^{ - 2}}} \right]$ |
| $(b)$ Coefficient of viscosity | $(ii)$ $\left[ {{M^1}{L^{ - 1}}{T^{ - 1}}} \right]$ |
| $(iii)$ $\left[ {{M^1}{L^{ - 1}}{T^{ - 2}}} \right]$ |