Answer: C) Convex Explanation: Convex mirror is used as rear view mirror in vehicles. Because the image is smaller, more image can fit onto the mirror, so a convex mirror provides for a larger field of view than a plane mirror. This is why they are useful.

The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core. There are two types of Shadow zones: one for P waves and one for S waves.   P wave shadows between 104-140 degree, both sides; S wave shadow from 105 of one side to 105 of the other.

Answer: C) Some Americans were accused of being Communist agents. Explanation:

Answer: B) Gupta period Explanation:

Answer: A) Dragon flies Explanation: Dragon flies have legs but they cannot walk.

Answer: A) TRUE Explanation: Air or gas can build up in the pleural space and when this happens, it's called a pneumothorax. Hence the given statement is TRUE.

Answer: A) a pair of scissors Explanation: Any of the basic mechanical devices for applying a force are called simple machines. There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work.