Mass of bullet, m1 = 10g = 0.01 kg
Velocity of bullet v1 = 200 m/s
Mass of block with the bullet as bullet gets embedded in it, m2 = 2+0.01 = 2.01 kg
Recoil velocity v2
According to the law of conservation of momentum m1 x v1 = m2 x v2
0.01 x 200 = 2.01 x v2