Q52. Number of molecules having bond order 2 from the following molecules is $\_\_\_\_$ $\mathrm { C } _ { 2 } , \mathrm { O } _ { 2 } , \mathrm { Be } _ { 2 } , \mathrm { Li } _ { 2 } , \mathrm { Ne } _ { 2 } , \mathrm {~N} _ { 2 } , \mathrm { He } _ { 2 }$