Semi-conductors are materials that a) are good conductors. b)allow electron flow and resist neutron flow. c)have insulator and conductor properties. d)allow neutron flow. semi-conductors are materials that have insulator and conductor properties.

c)have insulator and conductor properties.

Explanation:

Semiconductors, as the name suggest have properties of both insulators and conductors. Until the current/voltage applied to them reaches a particular threshold they work like an insulator. Once the threshold is crossed they behave like a conductor. This property makes them very useful in electronic devices. In fact almost all the electronic equipment in today's age use semiconductors in some way or the other.

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

read more on -

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.