Which of the following hydrides is electron-deficient?

In the following combinations of logic gates,the outputs $A, B$ and $C$ are respectively

$A$ car $P$ approaching a crossing at a speed of $10 \, m/s$ sounds a horn of frequency $700 \, Hz$ when $40 \, m$ in front of the crossing. The speed of sound in air is $340 \, m/s$. Another car $Q$ is at rest on a road which is perpendicular to the road on which car $P$ is reaching the crossing. The driver of car $Q$ hears the sound of the horn of car $P$ when he is $30 \, m$ in front of the crossing. The apparent frequency heard by the driver of car $Q$ is ...... $Hz$.

Consider the following statements for $X = \dot{C}H_3$ and $Y = \dot{C}F_3$:
$(I)$ When $X$ dimerises,the bond angle decreases.
$(II)$ When $X$ dimerises,the bond angle increases.
$(III)$ In the $X-Y$ molecule,the $C-C$ bond length is less than that in the $Y-Y$ molecule.
$(IV)$ The bond angle in $X$ is greater than that in $Y$.

Which of the following is not true for a eukaryotic cell?

In a $\triangle ABC$,$a^2 \sin 2C + c^2 \sin 2A$ is equal to (in $\Delta$)