Which one of the following elements is not an essential micronutrient for plant growth?

The resultant capacitance between $A$ and $B$ in the figure is.....$\mu F$

$\cos A \cos 2 A \cos 4 A \ldots \cos 2^{n-1} A$ equals

If the ratio of diameters,lengths and Young's moduli of steel and brass wires shown in the figure are $p, q$ and $r$ respectively,then the corresponding ratio of increase in their lengths would be

$A$ husband and wife have normal vision,but the fathers of both of them were colour blind. What is the probability of their first daughter being colour blind (in $\%$)?

Which of the following isomerism is not possible for complexes having molecular formulae?
$(I) Pt(SCN)_2 \cdot 3PEt_3$,$(II) CoBr \cdot SO_4 \cdot 5NH_3$,$(III) FeCl_2 \cdot 6H_2O$