No. of atoms in 1g ofO2(g)=2×321×6.023×1023=0.38×1023No. of atoms in 1g ofNi(s)=58.21×6.023×1023=0.10×1023No. atoms in 1g ofB(s)=10.81×6.023×1023=0.56×1023No. of atoms in 1g ofN2(g)=2×281×6.023×1023=0.43×1023Thus, 1gB(s) contains the largest number of atoms.