In a rectangle $ABCD$ where $BC = 2AB$,the moment of inertia will be minimum about which axis?

If two of the lines represented by $2x^3 + x^2y + y^3 = 0$ are mutually perpendicular,then the slope of the third line is

$A$ 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 (see figure). 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 .... $Hz$.

When acetaldehyde is reacted with $LiAlH_4$,what is the product formed?

In the figure shown, if the internal resistance of the battery is $1\, \Omega$, the reading of the ammeter will be ............... $A$.

The length of the common chord of the two circles $x^2+y^2-4y=0$ and $x^2+y^2-8x-4y+11=0$ is