Aballoon is negatively charged by rubbing and then clings to a wall. does this mean that the wall is positively charged? why or why not?

When you rub the ballon, it steals electrons from the surface of the thing that is used to rub it.

Now, the electrons are un the surface of the ballon, and when you put it near the wall, the electrons of the wall are repelled by the large amount of electrons in the ballon, leaving only the positive charge in the surface of the wall, this positive surface is atracted by the ballon (and the ballon by the positive surface) and this is why the ballon clongs to the wall.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.