Which of the following is not a polymer?

The normal at a point on the parabola $y^2=4x$ passes through $(5,0)$. If two more normals to this parabola also pass through $(5,0)$,then the centroid of the triangle formed by the feet of these three normals is

$A$ hereditary disease which is never passed on from father to son is

The triangle formed by the lines $2x^2+xy-6y^2=0$ and $x+y-1=0$ is

When an excess of $NaOH$ solution is added to a solution of potassium alum,what do we obtain?

If the line $y=2x+c$ is a tangent to the circle $x^2+y^2=5$,then a value of $c$ is