Which of the following taxonomic categories of the housefly is incorrectly matched?

$A$ ladder is leaned against a smooth wall and it is allowed to slip on a frictionless floor. Which figure represents the track of its centre of mass?

If $f(x) = \frac{x^2-10x+25}{x^2-7x+10}$ and $f$ is continuous at $x = 5$, then $f(5)$ is equal to

Two concentric coils of $10$ turns each are placed in the same plane. Their radii are $20 \ cm$ and $40 \ cm$ and carry $0.2 \ A$ and $0.3 \ A$ current respectively in opposite directions. The magnetic induction (in $T$) at the centre is

$A$ simple pendulum performs simple harmonic motion about $x=0$ with an amplitude '$a$' and time period '$T$'. The speed of the pendulum at $x=\frac{a}{2}$ is

In the reaction sequence,$C_2H_5Cl + KCN$ $\xrightarrow{C_2H_5OH} X$ $\xrightarrow[\Delta]{H_3O^+} Y$. What is the molecular formula of $Y$?