The quantum number of four electrons are given below :
n = 4, l = 2, m_l =–2, m_s = –1/2
n = 3, l = 2, m_l = 1, m_s = +1/2
n = 4, l = 1, m_l = 0, m_s = +1/2
n = 3, l = 1, m_l = 1, m_s = –1/2
The correct order of their increasing enegies will be :

In order to oxidise a mixture of one mole of each of FeC₂O₄, Fe₂(C₂O₄)₃, FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is :

The lathanide ion that would show colour is :

The correct order of the spin-only magnetic moment of metal ions in the following low-spin complexes, [V(CN)₆]^4–,[Fe(CN)₆]^4–, [Ru(NH₃)₆]³⁺, and [Cr(NH₃)₆]²⁺ , is :