$A$ metal nitrate reacts with $KI$ to give a black precipitate which on addition of excess of $KI$ converts into an orange-colored solution. The cation of the metal nitrate is

The mid-point of a chord of the ellipse $x^2+4y^2-2x+20y=0$ is $(2, -4)$. The equation of the chord is

$A$ thin metallic spherical shell contains a charge $Q$ on it. $A$ point charge $+q$ is placed at the centre of the shell and another charge $q'$ is placed outside it as shown in the figure. All the three charges are positive. The force on the charge at the centre is:

Fluorosis disease is caused due to the reaction of ...... with excess of fluoride in the body.

$A$ transistor is connected in common emitter $(CE)$ configuration. The collector supply is $8 \ V$ and the voltage drop across a resistor of $800 \ \Omega$ in the collector circuit is $0.5 \ V$. If the current gain factor $\alpha$ is $0.96$,find the base current in $\mu A$.

$A$ circular loop of radius $0.3 \ cm$ lies parallel to a much bigger circular loop of radius $20 \ cm$. The centre of the small loop is on the axis of the bigger loop. The distance between their centres is $15 \ cm$. If a current of $2.0 \ A$ flows through the smaller loop,then the flux linked with the bigger loop is: