Question

Speed of light in vacuum is $km{s}^{-1}$

• A. $3\times {10}^8$
• B. $3\times {10}^5$
• C. $3\times {10}^6$
• D. $3\times {10}^7$

Answer 1

The correct option is B $3\times {10}^5$

We know $1km=1000m$
Speed of light in vacuum is $3\times {10}^{8}m{s}^{-1}=\frac{3\times {10}^8}{1000}=3\times {10}^{5}km{s}^{-1}$