Statement (A): One mole of Calcium ions  ${\text{(Ca}}^{+2})$ containing $6.023\times {10}^{23}$${\text{Ca}}^{+2}$   ions

 Statement (B): Atomic mass of chlorine is 35.5

 Statement (C): The units of vapour density are gm/c.c

One mole of Calcium ions ${\text{(Ca}}^{+2})$  containing   $6.023\times {10}^{23}$  ${\text{Ca}}^{+2}$ ions  

Atomic mass of chlorine is 35.5

Vapour density has no units because it is a relative quantity.

$\text{Vapor\hspace{0.17em}density,V.D =}\frac{\text{Density\hspace{0.17em}of gas (g/c.c)}}{\text{Density of hydrogen (g/c.c)}}$            

 Note: Here, both denominator and numerator have same units. Hence, there is no units in resultant quantity is measured