The formal charges on the atoms marked as (1) to (4) in the Lewis representation of \( \mathrm{HNO_3} \) molecule respectively are
From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :
Six point charges are kept \(60^\circ\) apart from each other on the circumference of a circle of radius \( R \) as shown in figure. The net electric field at the center of the circle is ___________. (\( \varepsilon_0 \) is permittivity of free space)
Object is placed at $40 \text{ cm}$ from spherical surface whose radius of curvature is $20 \text{ cm}$. Find height of image formed.