Using a good compound bright field microscope with a resolving power of 0.3 μm, a 10× ocular lens, and a 100× oil immersion lens, would you be able to discern two objects separated by 3 μm? 0.3 μm? 300 nm? 3000 Å?

Yes, it could discern all of them.

Explanation:

A compound bright field microscope can be used to illuminate samples in light microscopes. It has a very high resolution and it could detect samples as small as 200 to 300 nanometers. So, yes it could discern two objects separated by 3μm, 0.3μm, 300nm,3000Å.

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.