The correct option is Its velocity is zero and acceleration is approximately $9.8 m s^{-2}$..
Explanation
This kinematics of an object undergoing vertical motion under the influence of gravity. Such motion is an example of uniformly accelerated motion where the acceleration due to gravity ($g$) acts constantly towards the center of the Earth.
Detailed Analysis:
- Velocity at the Highest Point: When an object is thrown vertically upwards, its velocity gradually decreases due to the retarding force of gravity. At the highest point of its path, the object momentarily comes to rest before reversing its direction to fall downwards. Therefore, the instantaneous velocity is zero.
- Acceleration at the Highest Point: The force of gravity acts on the object continuously throughout its flight, regardless of its position or velocity. Consequently, the object experiences a constant acceleration due to gravity ($g$), which is approximately $9.8 \, m/s^2$ acting downwards.
- Conclusion: Even though the velocity is zero at the peak, the acceleration is not zero. If acceleration were zero, the velocity would not change, and the object would remain suspended in the air indefinitely.
Key Takeaway:
Zero velocity does not imply zero acceleration. In vertical motion under gravity, acceleration is constant ($9.8 \, m/s^2$) at all points, including the highest point where velocity is momentarily zero.