Answer:
to help people breach in fresh air
Explanation:
Answer:
Noble gases because they have a full outer shell of electrons.
Explanation:
Noble gases usually called inert gases are generally non reactive gases. They belong to group 18 elements.They tend to not gain the electron or not give up a electron as they have full valence shells. Because they already have full valence shell and therefore full outer energy level, they are very stable and hardly react with any other elements.
Answer:
infrared waves
radio waves
ultraviolet waves
Explanation:
Radio waves are used for communication such as television and radio.
Infrared light is used by electrical heaters, cookers for cooking food, and by infrared cameras which detect people in the dark.
Ultraviolet radiation can kill bacteria that are present in water - this sterilises the water and makes it safe to drink.
The sonar pulse takes t=4.2 s to reach the ocean bottom and then to travel back tothe ship. If we call d the depth of the ocean bottom, this means that the sonar pulse covered a distance equal to 2d in a time of 4.2 s.
The speed of the sonar pulse is the speed of sound in water at 25C, so looking at the table is v=1493 m/s. Using the relationship
between space and time for a uniform motion, and keeping in mind that the total distance covered by the pulse is 2d, we can write:
which becomes
so, the ocean bottom is 3135 m deep.