The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is :

[Given : The threshold frequency of platinum is 1.3 $$\times$$ 10¹⁵ s^$$-$$1 and h = 6.6 $$\times$$ 10^$$-$$34 J s.]

The pair, in which ions are isoelectronic with AI³⁺ is :

The energy of one mole of photons of radiation of wavelength 300 nm is

(Given : h = 6.63 $$\times$$ 10^$$-$$34 J s, N_A = 6.02 $$\times$$ 10²³ mol^$$-$$1, c = 3 $$\times$$ 10⁸ m s^$$-$$1)

Consider the following pairs of electrons

(A) (a) n = 3, $$l$$ = 1, m₁ = 1, m_s = + $${1 \over 2}$$

      (b) n = 3, 1 = 2, m₁ = 1, m_s = + $${1 \over 2}$$

(B) (a) n = 3, $$l$$ = 2, m₁ = $$-$$2, m_s = $$-$$$${1 \over 2}$$

      (b) n = 3, $$l$$ = 2, m₁ = $$-$$1, m_s = $$-$$$${1 \over 2}$$

(C) (a) n = 4, $$l$$ = 2, m₁ = 2, m_s = + $${1 \over 2}$$

      (b) n = 3, $$l$$ = 2, m₁ = 2, m_s = + $${1 \over 2}$$

The pairs of electrons present in degenerate orbitals is/are :