OR: Is there any point where acceleration is parallel to the velocity in projectile motion?
At the highest point of the parabolic path, the vertical component of the velocity of the projectile is zero. So, only horizontal component of the velocity remains which acts horizontally. Since acceleration due to gravity always acts vertically downward, at the highest point, it is perpendicular to the velocity.
There is not any point where acceleration is parallel to the velocity. It is because acceleration due to gravity always acts vertically downwards and the horizontal component of the velocity is never zero in projectile motion.
[Read: Projectile Motion]