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Sound wave needs medium to travel
as energy which travels in this wave is because of transfer from one particle to another particle
If there is no medium then energy can not be transferred and sound wave will not travel
so in vacuum we can not listen sound
similarly here air is removed it means there is no medium inside the jar to travel the sound and hence we can not hear it
Option B is correct
Without air, the sound waves cannot travel to the ear.
First let's convert the time in seconds:

The current is defined as the quantity of charge flowing through a certain section of a circuit per unit of time:

Using I=10 A, and

, we can find the amount of charge flown through the hair dryer in this time:

The charge of a single electron is

, so the number of electrons flown through the hair dryer is the total charge divided by the charge of a single electron:
Explanation:
Given that,
Initial speed of the object, u = 1 m/s
Acceleration of the object, 
We need to find the time when the object comes at rest (v=0). Let it is given by :


t = 1 second
So, the object will comes to rest at 1 second. Hence, this is the required solution.
Answer:
yes; yes
Explanation:
Phases of the moon refers to the shapes of the moon due to the lit part of it visible from the Earth. On a new moon day, the moon comes between the sun and the earth such that the lit portion is not visible from the Earth. On a full moon day, the earth comes between the sun and the moon and the whole lit part is visible.
When one would view the earth from the moon, the earth would also be visible as going through the phases. The order would be reversed. Understand this with the following example, On a new moon day, the Earth would be visible completely lit from the moon. So it will be full Earth day on the moon. On a full moon day, the lit side of the Earth would be completely away and hence, from the moon, new earth would be there.
Answer:

Explanation:
Assuming that the pacific plate moved 178 km in 1.76 million years.
s = Distance = 178 km
t = Time taken = 1.76 million years
Speed is given by

The speed of the plate is 