21. Comment on the thermodynamic stability of NO (g), given

½ N₂ (g) + ½ O₂ (g) → NO (g); Δ_rH^? = 90 kJ mol^–1

NO (g) + ½ O₂ (g) → NO₂ (g); Δ_rH^? = –74 kJ mol^–1

HCP crystal is made of A ions and B ions are arranged in 2/3rd of octahedral voids. The simplest formula of compound is :-

Which of the following is a carbonate ore ?

Which of the following complex is paramagnetic, inner orbital complex and coloured :-

The orbital angular momentum of 3d electron is

For the reaction, CaCO₃(s) → CaO(s) + CO₂(g) △H = 82.8 kJ at 25°C, △U at 25°C is