Which of the following is the correct increasing bond order for the given diatomic species?

• $\mathrm{NO}<{\mathrm{O}}_2^{-}<{\mathrm{C}}_2^{2-}<{\mathrm{He}}_2^{-}$

• ${\mathrm{C}}_2^{2-}<{\mathrm{He}}_2^{2+}<{\mathrm{O}}_2^{-}<\mathrm{NO}$

• ${\mathrm{He}}_2^{+}<{\mathrm{O}}_2^{-}<\mathrm{NO}<{\mathrm{C}}_2^{2-}$

• ${\mathrm{O}}_2^{-}<\mathrm{NO}<{\mathrm{C}}_2^{2-}<{\mathrm{He}}_2^{+}$

The wavelength of a spectral line emitted by hydrogen atom in the Lyman series is $\frac{16}{15\mathrm{R}}\mathrm{cm}$.
The value of n, will be

                               [R=Rydberg constant]

• 1

• 2

• 3

• 4

At relatively high pressure, vander Waal's equation reduces to:

• pV=RT

• pV=RT$-\frac{\mathrm{a}}{\mathrm{V}}$

• pV=RT$-\frac{\mathrm{a}}{{\mathrm{V}}^2}$

• pV=RT+pb

The first ionisation enthalpy of boron is less than beryllium because:

• Boron has high nuclear charge

• The size of boron atom is more than beryllium atom

• p-subshell of boron has only one electron

• The size cit boron atom is less than beryllium atom

As the temperature is raised from 20°C to 40C, the average kinetic energy of neon atoms changes by a factor:

• $\frac{313}{293}$

• $\sqrt{\left(\frac{313}{293}\right)}$

• $\frac{1}{2}$

• 2

The dipole moment of HBr is 2.60 x 10^-30 Cm and the interatomic spacing is 1.41 $\stackrel{\circ }{\mathrm{A}}$ .The percent ionic character of HBr is:

• 11.5%

• 10.1%

• 8.2%

• 4.1%

7.

For an electron whose x-positional uncertainity is 1x 10^-10 m, the uncertainity in the x-component of the velocity in ms^-1 will be of the order of:

$(\mathrm{Data} : {\mathrm{m}}_{\mathrm{e}} = 9\times {10}^{-31} \mathrm{Kg} , \mathrm{h}= 6.6 \times 10{ }^{-34} \mathrm{JS} )$

• 10⁶

• 10³

• 10¹²

• 10¹⁵

Which of the following statement(s) is/are correct regarding shielding effect?

• The magnitude of screening effect do not depends upon the number of inner electrons

• The magnitude of effective nuclear charge decreases in a period.

• Greater the shielding effect, lower will be the atomic radii

• For a given 'orbit' the shielding effect of electron belonging to different subshell decrease in the order s > p > d >f

When NaNO₃ is heated in a closed vessel oxygen is liberated and NaNO₃ is left behind,

At equilibrium:

• addition of NaNO₂ favours reverse reaction

• addition of NaNO₃ favours reverse reaction

• increasing temperature favours forward reaction

• decreasing temperature favours backward reaction

${\mathrm{CaCO}}_{3 } \rightleftharpoons \mathrm{CaO} + {\mathrm{CO}}_2 \mathrm{reaction} \mathrm{in} \mathrm{lime} \mathrm{kiln} \mathrm{goes} \mathrm{to} \mathrm{completion} \mathrm{because}$:

• CaO does not react to CO₂  to give CaCO₃

• backward reaction is very low

• CO₂ formed escapes out

• None of the above