Answer:
The mass of the earth, 
Explanation:
It is given that,
Time taken by the moon to orbit the earth, 
Distance between moon and the earth,
We need to find the mass of the Earth using Kepler's third law of motion as :
So, the mass of the earth is 
. Hence, this is the required solution.
the answer of this question is helium
Explanation:
It represents the direction of flow of positive charge but is treated as a scalar quantity because current follows the laws of scalar addition and not the laws of vector addition. The angle between the wires carrying current does not affect the total current in the circuit.
Answer:
c) Very dangerous and users must not override devices designed to protect from exposures.
Explanation:
X-ray is a form of high energy electromagnetic radiation and are part of the electromagnetic spectrum.
X-ray radiation from diffraction and fluorescence instruments is very dangerous because of their high energy and wavelength.
Hence, users must not override devices designed to protect from exposures. The best shielding device to protect one from exposure is Lead.
The ozone layer that is inside the stratosphere blocks UV radiation.
The ozone layer contains high concentrations of ozone relative to other parts of the atmosphere. This was discovered by Charles Fabry and Henri Buisson who are both French Physicists.
The ozone in the earth's stratosphere is created through ultraviolet light striking a group of ordinary oxygen molecules containing two oxygen atoms, subsequently splitting them into individual oxygen atoms and finally these said atomic oxygen then combines with unbroken O2 to create ozone (O3).
