Is the chorion the yolk of the egg

Yes

Explanation:

Inside the egg are a series of fluid-filled membranes that permit the embryo to survive: the amnion, allantois, yolk sac, and chorion. Around the chorion is the albumin or "white" of the egg, and an outer shell protects the whole egg, preventing drying while still permitting air to reach the embryo.

The diagram will help you below:

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.