$.$: $---$ All hydrogen atoms $1.$ Have the same resonance frequency. $2.$ Resonated at different frequencies depending on their environment. $3.$ Are attached to carbon. $4.$ Resonated at about the same frequency as carbon. $$: $2$ What is shielding in NMR$?1.$ Using a curved piece of metal to block an opponent's attack. $2.$ Putting metal around an RF source. $3.$ When the magnetic moment of an atom blocks the full induced magnetic field from surrounding nuclei. $4.$ Blocking parts of the molecule from RF radiation. $---$