$A$ potentiometer wire of length $1\,m$ is connected in series with a resistance of $490\,\Omega$ and a battery of $2\,V$. If the potential gradient is $0.2\,mV/cm$,then the resistance of the potentiometer wire is ............$\Omega$. (in $.9$)

Match the taxonomic categories given in column $I$ with their feature given in column $II$.

Column $I$	Column $II$
$A$. Taxon	$I$. Basic unit of classification
$B$. Species	$II$. $A$ taxonomic group of any rank
$C$. Phylum	$III$. Division is the same category in case of plants
$D$. Genus	$IV$. Identified based on a number of similar characters
$E$. Order	$V$. Group of related species having more characters in common with other species

In the reaction $A + 2B \rightleftharpoons 2C + D$,the initial concentration of $B$ was $1.5$ times that of $[A]$. At equilibrium,the concentrations of $A$ and $B$ became equal. The equilibrium constant $K_c$ for the reaction is:

If $\overrightarrow{a}=\hat{i}-\hat{j}-\hat{k}$ and $\overrightarrow{b}=\lambda \hat{i}-3 \hat{j}+\hat{k}$ and the orthogonal projection of $\overrightarrow{b}$ on $\overrightarrow{a}$ is $\frac{4}{3}(\hat{i}-\hat{j}-\hat{k})$, then $\lambda$ is equal to

Who is affected by the consumption of drugs during pregnancy?

The two surfaces of a biconvex lens have the same radii of curvature. This lens is made of glass with a refractive index of $1.5$ and has a focal length of $10 ~cm$ in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex surfaces touch each other. If this combination lens is immersed in water (refractive index $=$ $4/3$),its focal length (in $cm$) is: