$CrO_3$ dissolves in aqueous $NaOH$ to give:

The angle of elevation of the top of the tower observed from each of the three points $A, B, C$ on the ground,forming a triangle,is the same angle $\alpha$. If $R$ is the circum-radius of the triangle $ABC$,then the height of the tower is

The number of molecules of $CO_2$ liberated by the complete combustion of $0.1 \text{ mol}$ of graphite in air is:

For skywave propagation of a $10\, MHz$ signal,what should be the minimum electron density in the ionosphere?

In a balanced meter bridge,the resistance of the bridge wire is $0.1 \Omega/cm$. An unknown resistance $X$ is connected in the left gap and $6 \Omega$ in the right gap. The null point divides the wire in the ratio $2:3$. Find the current drawn from a battery of $5 \text{ V}$ having negligible internal resistance. (in $A$)

In an acute angled triangle,$\cot B \cot C + \cot A \cot C + \cot A \cot B$ is equal to