Litmus paper can be used to check whether a substance has acidic or basic property.Acids like HCl turns blue litmus red.And bases like NaOH turns red litmus blue.

What will be the color of red litmus on a neutral salt like NaCl?

Also what will be the colour of blue litmus on NaCl?Will there be any change?

See change in the litmus paper depends on the ph value of the solution. As per the question nacl is formed by naoh and hcland both are strong base and acid so ph value of nacl will be almost neutral

Approved

sodium chloride is neutral and hence its colour will be green.blue litmus is already basic since litmus when neutral will be purple. so colour of blue litmus will differ between green and dark blue colour depending on the ph.