The molarity of one molal glucose solution having density of 1.2 g/mL is

$$\begin{gathered} \mathrm{density}=\frac{\mathrm{mass}}{\mathrm{volume}} \\ 1.2=\frac{\mathrm{mass}}{1000}=1200 \mathrm{g} \end{gathered}$$

Molality is 1 m (number of moles of solute per kg of solvent) and 1 m signifies 1 mole of solute present in 1 kg or (1000 g) of water. 

Mass of solute is 200 g (1200 g - 1000 g).

$$\begin{gathered} \mathrm{Molarity}=\frac{\mathrm{mass}}{\mathrm{molar} \mathrm{mass}}\times \frac{1}{\mathrm{vol} \mathrm{in} \mathrm{L}} \\ \mathrm{Molarity}=\frac{200}{180.156 }\times \frac{1}{1}=1.01 \mathrm{M} \end{gathered}$$