Blood must pass through the ........ to reach the left side of the heart.

For a certain organ pipe,three successive resonance frequencies are observed at $425 \, Hz$,$595 \, Hz$,and $765 \, Hz$ respectively. If the speed of sound in air is $340 \, m/s$,then the length of the pipe is .... $m$

How many $EDTA$ molecules are required to make an octahedral complex with a $Ca^{2+}$ ion?

Two identical balls $A$ and $B$ are released from the positions shown in figure. They collide elastically on the horizontal portion $MN$. The ratio of the maximum height attained by $A$ and $B$ after the collision will be: (neglect friction)

Which oxide of nitrogen is obtained when ammonium nitrate is heated at $250\,^oC$?

Match column-$I$ with column-$II$ and choose the correct combination from the options given below.

Column-$I$	Column-$II$
$A$. National Botanical Research Institute	$I$. Carolus Linnaeus
$B$. Indian Botanical Garden	$II$. Taxon
$C$. Binomial Nomenclature	$III$. Howrah (India)
$D$. $A$ unit of Classification	$IV$. Lucknow