Some reactions of $NO _2$ relevant to photochemical smog formation are

Identify $A , B , X$ and $Y$
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 _____. 
There is a number of factors that contribute to the pollution of the environment. Some of the major causes of atmospheric pollution are given below -