When the course deviation indicator (CDI) needle is centered during an omnireceiver check using a VOR test signal (VOT), the omnibearing selector (OBS) and the TO/FROM indicator should read:

0° FROM or 180° TO

Explanation:

A course deviation indicator or the CDI may be defined as an avionics tool or instrument that is used in the aircraft navigation which is used to determine an aircraft's lateral position with relation to a course.

While using the VOT service, we should tune the VOT frequency of the VOR receiver. And with the CDI leveled centered, the omnibearing selector or the OBS should read as 0° with the TO/FROM indicator showing 'FROM'. Else the OBS should read as 180° with the TO/FROM indication showing 'TO.'

b) phosphorus pentoxide

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.