1)Why is ground state of carbon more stable than its excited state despite the fact that half-filled orbitals are more stable than fully-filled orbitals?
2)Two plano-concave lenses(A and B) of glass of refractive index 1.5 each have radii of curvature 25cm and 20cm.They are placed in contact with their curved surface towards each other and space between them is filled with liquid of refractive index 4/3.
Find the focal length of the combination.
3)A plano-convex lens fits exactly into a plano-concave lens.Their plane surfaces are parallel to each other.If the lenses are made of different materials of refractive indices and and radius of curvature ,find the focal length of the combination.
4)What are some cool tricks to solve a network of resistors?
Like for example what should be our approach while solving a weird network of resistors for net resistance?
5)Why do d-block elements show great variations in their properties and why do they have variable oxidation state?
Please help me.Thanks!