In the given figure, the magnetic field at the centre will be:

If $p \Rightarrow (q \vee r)$ is false,then the truth values of $p, q, r$ are respectively

If $\theta$ is the angle between the tangents from $(-1,0)$ to the circle $x^2+y^2-5x+4y-2=0$,then $\theta$ is equal to

Among the following,which is water insoluble?

If $\alpha, \beta, \gamma$ are the roots of the equation $x^3-6x^2+11x-6=0$ and if $a=\alpha^2+\beta^2+\gamma^2$,$b=\alpha\beta+\beta\gamma+\gamma\alpha$ and $c=(\alpha+\beta)(\beta+\gamma)(\gamma+\alpha)$,then the correct inequality among the following is

Match List-$I$ with List-$II$ and select the correct answer using the codes given below:

List-$I$	List-$II$
$(1)$ Heavy water	$(a)$ Bicarbonates of $Ca$ and $Mg$ in water
$(2)$ Temporary hard water	$(b)$ No foreign ions in water
$(3)$ Soft water	$(c)$ $D_2O$
$(4)$ Permanent hard water	$(d)$ Sulphates and chlorides of $Ca$ and $Mg$ in water