[" 1.] A motor car is going due north at a speed of "50km/h" ."],[" It makes a "90^(@)" left turn without changing the speed."],[" The change in the velocity of the car is about "],[" (a) "50km/h" towards west "],[" (b) "70km/h" towards south-west "],[" (c) "70km/h" towards north-west "],[" (d) zero."]