The standard enthalpy of formation \((\Delta _f\,H^o_{298})\) for methane, \(CH_4\) is \(-74.9\,kJ\,mol^{-1}\) . In order to calculate the average energy given out in the formation of a \(C - H\) bond from this it is necessary to know which one of the following?

Match List \(I\) With List \(II\)

List \(I\) (compounds)	List \(II\) (Value of \(Pk_a\))
\(A\). ethanol	\(I\). \(10.0\)
\(B\). phenol	\(II\). \(15.9\)
\(C\). \(m\)-nitrophenol	\(III\). \(7.1\)
\(D\). \(p\)-nitrophenol	\(IV\). \(8.3\)

Choose the correct answer from the options given below:

Two nucleotides are joined together by a linkage known as :

The correct order of the ionic radii of \(O ^{2-}, N ^{3-}, F ^{-}, Mg ^{2+}, Na ^{+}\) and \(Al ^{3+}\) is 

When \(9.65\) ampere current was passed for \(1 .0\) hour into nitrobenzene in acidic medium, the amount of \(p-\) amino-phenol produced is .............. \(\mathrm{g}\)

Which one of the following molecules is expected to exhibit diamagnetic behaviour ?

Arrange the bonds in order of increasing ionic character in the molecules.
[\(\mathrm{LiF}, \mathrm{K}_2 \mathrm{O}, \mathrm{N}_2, \mathrm{SO}_2\) and \(\mathrm{CIF}_3\)]

If \(y(\theta)=\frac{2 \cos \theta+\cos 2 \theta}{\cos 3 \theta+4 \cos 2 \theta+5 \cos \theta+2}\) then at \(\theta=\frac{\pi}{2}, y^{\prime \prime}+y^{\prime}+y\) is equal to :

If \({\Delta _1} = \left| {\begin{array}{*{20}{c}}
  x&{\sin \,\theta }&{\cos \,\theta } \\ 
  {\sin \,\theta }&{ - x}&1 \\ 
  {\cos \,\theta }&1&x 
\end{array}} \right|\) and \({\Delta _1} = \left| {\begin{array}{*{20}{c}}
  x&{\sin \,2\theta }&{\cos \,\,2\theta } \\ 
  {\sin \,2\theta }&{ - x}&1 \\ 
  {\cos \,\,2\theta }&1&x 
\end{array}} \right|\), \(x \ne 0\) ; then for all \(\theta  \in \left( {0,\frac{\pi }{2}} \right)\)

Let the moment of inertia of a hollow cylinder of length \(30\, cm\) (inner radius \(10\, cm\) and outer radius \(20\, cm\)), about its axis be \(I\). The radius of a thin cylinder of the same mass such that its moment of inertia about its axis is also \(I\), is ......... \(cm\).

Identify the correct statements from the following descriptions of various properties of electromagnetic waves. \(A\). In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field. \(B.\) The energy in electromagnetic wave is divided equally between electric and magnetic fields. \(C.\) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave. \(D.\) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other. \(E.\) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light. Choose the most appropriate answer from the options given below:

An \(EM\) wave propagating in \(x\)-direction has a wavelength of \(8\,mm\). The electric field vibrating \(y\) direction has maximum magnitude of \(60\,Vm ^{-1}\). Choose the correct equations for electric and magnetic fields if the \(EM\) wave is propagating in vacuum

In which of the following complexes the CFSE, \(\Delta_{\mathrm{o}}\) will be equal to zero?