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) 
A solid sphere of radius \(4a\) units is placed with its centre at origin. Two charges \(-2q\) at \((-5a, 0)\) and \(5q\) at \((3a, 0)\) is placed. If the flux through the sphere is \(\frac{xq}{\in_0}\) , find \(x\)
200 ml of an aqueous solution contains 3.6 g of Glucose and 1.2 g of Urea maintained at a temperature equal to 27$^{\circ}$C. What is the Osmotic pressure of the solution in atmosphere units?
Given Data R = 0.082 L atm K$^{-1}$ mol$^{-1}$
Molecular Formula: Glucose = C$_6$H$_{12}$O$_6$, Urea = NH$_2$CONH$_2$