First, compute the standard deviation:
$\sigma = \frac{0.49}{\sqrt{490}} \approx 0.022136$

Using the 95% confidence level, the z-score is approximately $1.645$.$VaR = z \times \sigma = 1.645 \times 0.022136 \approx 0.03641$

Under the constant spread approach, the liquidity cost (LC) per unit is:
$LC = 0.5 \times spread = 0.5 \times 0.02 = 0.01$

The percentage increase in VaR due to the liquidity adjustment is:
$\frac{LC}{VaR} = \frac{0.01}{0.03641} \approx 0.2746$ or $27.46%$

Therefore, the constant spread liquidity adjustment raises the VaR by almost 27%.