Questions in circle

Select	Question
	The value of k so that ${{x}^{2}}+{{y}^{2}}+kx+4y+2=0$ and $2({{x}^{2}}+{{y}^{2}})-4x-3y+k=0$ cut orthogonally is
	If the circles ${{x}^{2}}+{{y}^{2}}+2ax+cy+a=0$ and ${{x}^{2}}+{{y}^{2}}-3ax+dy-1=0$ intersect in two distinct points $P$ and $Q$ then the line $5x+by-a=0$ passes through $P$ and $Q$ for
	The two circles ${{x}^{2}}+{{y}^{2}}-2x+22y+5=0$ and ${{x}^{2}}+{{y}^{2}}+14x+6y+k=0$ intersect orthogonally provided k is equal to
	A circle touches the x-axis and also touches the circle with centre at (0, 3) and radius 2. The locus of the centre of the circle is