The number of unpaired electrons in a chromic ion $Cr^{3+}$ (atomic number $= 24$) is

Which type of circulatory system is shown in the given figure?

$\sec ^2(\tan ^{-1} 2) + \operatorname{cosec}^2(\cot ^{-1} 3)$ is equal to

$A$ spring $40\,mm$ long is stretched by the application of a force. If $10\,N$ force is required to stretch the spring through $1\,mm$,then work done in stretching the spring through $40\,mm$ is ............. $J$.

The amount of copper metal deposited at the cathode on passing an electric current of $500 \, mA$ for $20 \, minutes$ in a cupric chloride solution is ............ $g$.

While a collector to emitter voltage is constant in a transistor,the collector current changes by $8.2 ~mA$ when the emitter current changes by $8.3 ~mA$. The value of forward current ratio is