The ionization enthalpy of a hydrogen atom is 1.312 × 10⁶Jmol⁻¹. The energy required to excite the electron in the atom from n = 1 to n = 2 is 

• 8.51 × 10⁵ Jmol−1

• 6.56 × 10⁵ Jmol⁻¹

• 7.56 × 10⁵ Jmol⁻¹

• 7.56 × 10⁵ Jmol⁻¹

Which of the following sets of quantum numbers represents the highest energy of an atom?

• n = 3, l = 1, m = 1, s = +½

• n = 3, l = 2, m = 1, s = +½

• n = 4, l = 0, m = 0, s = +½

• n = 4, l = 0, m = 0, s = +½

According to Bohr’s theory, the angular momentum of an electron in 5th orbit is

• 25h/ π

• 1.0h/π

• 10/π

• 10/π

Uncertainty in the position of an electron (mass = 9.1 × 10^–31 kg) moving with a velocity 300 ms–1, accurate upto 0.001%, will be

• 19.2 × 10^–2 m

• 5.76 × 10^–2 m

• 1.92 × 10^–2 m

• 1.92 × 10^–2 m

The “spin-only” magnetic moment [in units of Bohr magneton,(µB )] of Ni²⁺ in aqueous solution would be (Atomic number of Ni = 28) 

• 2.84

• 4.90

• 1

• 1

Which of the following sets of quantum numbers is correct for an electron in 4f orbital?

• n = 4, I =3, m = +4, s = + 1/ 2

• n = 3, I = 2, m = -2, S = + 1/2

• n =4, I = 3, m = +1, s = + 1/ 2

• n =4, I = 3, m = +1, s = + 1/ 2

Consider the ground state of Cr atom (Z = 24). The number of electrons with the azimuthal quantum numbers I =1 and 2 are respectively

• 12 and 4

• 16 and 5

• 16 and 4

• 16 and 4

18.

The wavelength of the radiation emitted, when in hydrogen atom electron falls from infinity to stationary state 1, would be (Rydberg constant = 1.097×10⁷ m^-1)

• 91 nm

• 9.1×10^-8 nm

• 406 nm

• 406 nm

If the given four electronic configurations,

(i) n = 4, l = 1

(ii) n = 4, l = 0

(iii) n = 3, l = 2

(iv) n = 3, l = 1

are arranged in order of increasing energy, then the order will be

• (iv) < (ii) < (iii) < (i)

• (ii) < (iv) < (i) < (iii)

• (i) < (iii) < (ii) < (iv)

• (iii) < (i) < (iv) < (ii)

Which of the following sets of quantum numbers represents the 19^th electron of Cr(Z = 24)?

• (4, 1, -1, +$\frac{1}{2}$)

• (4, 0, 0, +$\frac{1}{2}$)

• (3, 2, 0, -$\frac{1}{2}$)

• (3, 2, -2, +$\frac{1}{2}$)