Questions in circle

Select	Question
	The equation of polar of the point (1, 2)with respect to the circle ${{x}^{2}}+{{y}^{2}}=7$ , is
	The equation of the chord of contact, if the tangents are drawn from the point (5, –3) to the circle ${{x}^{2}}+{{y}^{2}}=10$ , is
	A line through (0,0) cuts the circle ${{x}^{2}}+{{y}^{2}}-2ax=0$ at A and B, then locus of the centre of the circle drawn on AB as a diameter is
	The radius of the circle, having centre at (2,1) whose one of the chord is a diameter of the circle ${{x}^{2}}+{{y}^{2}}-2x-6y+6=0$ is
	The intercept on the line $y=x$ by the circle ${{x}^{2}}+{{y}^{2}}-2x=0$ is AB, equation of the circle on AB as a diameter is
	The equation of the circle having as a diameter, the chord $x-y-1=0$ of the circle $2{{x}^{2}}+2{{y}^{2}}-2x-6y-25=0$ , is
	If the circles ${{x}^{2}}+{{y}^{2}}={{a}^{2}}$ and ${{x}^{2}}+{{y}^{2}}-2gx+{{g}^{2}}-{{b}^{2}}=0$ touch each other externally, then
	For the given circles ${{x}^{2}}+{{y}^{2}}-6x-2y+1=0$ and ${{x}^{2}}+{{y}^{2}}+2x-8y+13=0$ , which of the following is true
	A circle passes through (0, 0) and (1, 0) and touches the circle ${{x}^{2}}+{{y}^{2}}=9$ , then the centre of circle is
	If ${{x}^{2}}+{{y}^{2}}+px+3y-5=0$ and ${{x}^{2}}+{{y}^{2}}+5x$ $+py+7=0$ cut orthogonally, then p is