If medium between two charges is air, then value of constant k in SI units will be

Q. If medium between two charges is air, then value of constant k in SI units will be

1. 5 × 109 Nm²C-2
2. 7 × 109 Nm²C-2
3. 8 × 109 Nm²C-2
4. 9 × 109 Nm²C-2

Answer: 9 × 109 Nm²C-2