7.
is a special type of motion in which the only force acting upon an object is gravity.

a. terminal
b. air resistance
c. gravitational velocity
d. free fall

Free fall is a special type of motion in which the gravity is the only force that acting upon an object.

Explanation:

In the free fall the object have gravity force only. when you dropped the ball from top of the building, and it will start falling. The balls falls due to gravity. Imagine when you have held the ball in your hand, gravity is acting, but the frictional force between your fingers and ball is acting on the opposite side. When the ball is kept in air, gravity is the only force that acts on the ball. Hence in free fall, the object has no another forces except gravity.

it becomes positively charged by charging it

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.