Final answer:
Velocity is a vector quantity because it entails both magnitude and direction, whereas temperature is a scalar quantity as it does not have direction. The combination of displacement, velocity, and acceleration represents two vectors and a scalar.
Step-by-step explanation:
The correct answer to the question 'which one of the following is a vector quantity?' is D. Velocity. Velocity is a vector quantity because it has both magnitude and direction. For instance, a car traveling east along a freeway at 100 km/h is described by its velocity, consisting of a speed (magnitude) of 100 km/h and the direction which is east.
Regarding question 2, which is asking 'Which of the following contains two vectors and a scalar?' the correct answer is B. Displacement, velocity, and acceleration are all vector quantities since each has a magnitude and a direction. Speed is a scalar quantity because it has only magnitude and no direction, making none of the options containing 'speed' correct.
Finally, answering the question about temperature, 'A weather forecast states that the temperature is predicted to be -5°C the following day. Is this temperature a vector or a scalar quantity?', temperature is a scalar quantity. It is described fully by its magnitude, -5°C, and does not have or require a direction for its description.