The ccrrect statement with regard to ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_2^{-}$ is :

• both ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_2^{-}$ are equally stable

• both ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_2^{-}$ do not exist

• ${\mathrm{H}}_2^{-}$ is more stable than ${\mathrm{H}}_2^{+}$

• ${\mathrm{H}}_2^{+}$ is more stable than ${\mathrm{H}}_2^{-}$

Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atom in ground state is excited by monochromatic light of energy 12.1 eV. The spectral lines emitted by hydrogen according to Bohr's theory will be

• one

• two

• three

• four

According to Bohr's theory, which of the following correctly represents the variation of energy and radius of an electron in n^th orbit of H-atom?

• E_n $\propto \frac{1}{{\mathrm{n}}^2}$, r $\propto \frac{1}{{\mathrm{n}}^2}$

• E_n $\propto \frac{1}{{\mathrm{n}}^2}$, r $\propto {\mathrm{n}}^2$

• E_n $\propto$n², r $\propto$n²

• E_n $\propto$n, r $\propto \frac{1}{\mathrm{n}}$

The correct set of quantum numbers for the unpaired electron of a chlorine atom is :

• 2 , 0 , 0 , +$\frac{1}{2}$

• 2 , 1 , -1 , +$\frac{1}{2}$

• 3 , 1 , -1 , $\pm \frac{1}{2}$

• 3 , 0 , 0 , $\pm \frac{1}{2}$

Number of electron in one molecule of NH₃ :

• 17

• 34

• 7

• 10

76.

The value of magnetic quantum number for l = 3 :

• 0 , +1 , +2 , +3

• 0 , ± 1 , ± 2 , ± 3

• -1 , -2 , -3

• ± 1 , ± 2 , ± 3

Assertion : H₂S is stronger acid than PH₃.

Reason : S is more electronegative than P, conjugate base HS^- is more stable than H₂P^-.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false.

• If both assertion and reason are false.

If two elements X and Y have 3 and 6 electrons in its outermost shell , then the molecular formula of compound formed by the combination of X and Y :

• XY

• X₃Y

• X₂Y

• X₂Y₃

The probability of finding of three unpaired electron in nitrogen atom is defined by :

• Aufbau's principle

• Uncertainty principle

• Pauli's principle

• Hund's rule

$\mathrm{\alpha }$-particles can be detected by using

• thin aluminium sheet

• barium sulphate

• zinc sulphide screen

• gold foil