A is a simple closed curve, all of whose points are at the same distance from a fixed point.

Following are steps while constructing a line segment of length $5 cm$ using ruler. Which of the following steps is incorrect?

Step-1: First mark a point $A$ on paper.

Step-2: Place a ruler in such a way that its zero point coincide with point $A$.

Step-3: Draw a line from the point A of the measure of $4.5$ cm on the ruler.

Step-4: Now, name the end point as $Q$.

Step-5: AB is the required line segment.
 

Arrange the following steps to construct an angle of $120°$.

Step-1: Again, with $C$ as centre, without changing the radius, draw one more arc. Both arcs intersect at $D$.

Step-2: Draw a ray $OD$ with $O$ as initial point through the point $D$.

Now, measure of $\angle DOA=120°$.

Step-3: Draw a ray $OA$.

Step-4: Now, without changing the radius, keeping $B$ as centre, draw an arc. Both the arcs intersect at a point $C$.

Step-5: With $O$ as centre, draw an arc cutting $OA$ at $B$.
 

Arrange the following steps to construct perpendicular bisector of line segment $AB$.

Step-1: With the same radius and with $B$ as centre, draw another circle using compasses, which cuts the previous circle at $X$ and $Y$.

Step-2: Join $XY.$ Now is the required perpendi- cular bisector of $\overline{AB}$

Step-3: Draw a $\overline{AB}$ of any length.

Step-4: With $A$ as centre, using compasses, draw a circle. The radius of the circle should be more than half the length of $\overline{AB}$.

Following are the steps while constructing a perpendicular to a line $\text{'}I\text{'}$ through a point $\text{'}P\text{'}$ not on it. Out of these one of the steps is incorrect. Select the incorrect step.

Step-1: Given a line $I$ and a point $P$ not on it.

Step-2: With $P$ as centre, draw an are which intersects line $l$ at two points $L$ and $M$.

Step-3: With any convenient radius and with $L$ and $M$ as centres, construct two ares that intersect at a point, say $Q$, on the other side.

Step-4: Join $PQ$.
 

If $YA=AB$, then measure of $\angle XYC$ equals

Which of the following angles cannot be made using a ruler and a pair of compasses?

To draw a perpendicular bisector of a line segment $AB$, first draw a circle by taking _____ as centre and radius _____ of $AB$.