Oil can be used to reduce friction.
true or fales

take 100 mark for solving
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This is true.

Oil has a good consistency for reduction in tight areas of something. If you've ever played a recorder for band class or just for fun, you may have realized that every time you take it apart and put it together again it gets harder, and normally the recorder comes with a small container of oil that you rub between the two connecting pieces.

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.

answer and explanation;