To determine the number of compounds where Sulphur exhibits a +4 oxidation state, let's examine the oxidation state of Sulphur in each compound.
The compounds with Sulphur in the +4 oxidation state are \(H_2SO_3\), \(SOCl_2\), and \(SF_4\). Hence, the number of such compounds is 3.

The compounds with +4 oxidation state of Sulfur are H2SO3, SOCl2, and SF4, giving a total of 3.
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field \( B \) exists into the page. The bar starts to move from the vertex at time \( t = 0 \) with a constant velocity. If the induced EMF is \( E \propto t^n \), then the value of \( n \) is _____. 