If velocity of a galaxy relative to earth is $1.2 × 106 ms^{–2}$ then % increase in wavelength of light from galaxy as compared to the similar source on earth will be

0.4 %

Since $\frac{v}{c}=\frac{Δλ}{λ}$

$∴Δλ=\frac{v}{c}xλ$

or $\frac{Δλ}{λ}=\frac{1.2×10^6}{3×10^8}=\frac{12}{3}×\frac{10^5}{10^8}=4×10^{-3}$

$\frac{Δλ}{λ}×100=0.4$ i.e., 0.4%