Litmus paper is made from water-soluble dyes which are extracted from lichens. this paper is used as an acid-base indicator. which of these common household substances would turn blue litmus paper red? a) ammonia b) vinegar c) baking soda d) distilled water

B) vinegar

Explanation: Acids are those substances which when dissolved in water give ions. They turn blue litmus red.

Bases are those substances which when dissolved in water give ions. They turn red litmus blue.

Ammonia is a base which when dissolved in water forms ammonium hydroxide and gives ions and turns red litmus blue.

Vinegar is acetic acid and thus gives ions and turn blue litmus red.

Baking soda is a basic salt which turns red litmus blue.

Distilled water is neutral which shows no color change with red or blue litmus.

an obstruction

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.