Elements is the simplest form of a pure substance.They cannot be broken down into any thing else ,by either physical or chemical means.In contrasts compounds are pure substances like elements ,they are made up of two or more elements.Just like elements they can be broken down into simpler substances by chemical means,but unlike elements they can only be broken down by chemical means .not both physical and chemical means like elements can.
(I hope that this was helpful.)
Answer:
True
Explanation:
In 2019 was taken the first image of a supermassive black hole in the center of the galaxy M87 with the Event Horizon Telescope, which is a network of radio telescope located in different points of the Earth, with the purpose of making a telescope of the size of the Earth.
A radio telescope is an antenna that is capable to perceive the light in the radio part of the electromagnetic spectrum¹.
It is important to notice that in the picture what it can be seen is the effect that the black hole has in the nearby stars.
Key terms:
¹Electromagnetic spectrum: decomposition of light in its different wavelengths (from radio waves to gamma rays).
Solution :
Acceleration due to gravity of the earth, g 
Acceleration due to gravity at 1000 km depths is :
= 8.23 m/s
Acceleration due to gravity at 2000 km depths is :
= 6.73 m/s
Acceleration due to gravity at 3000 km depths is :
= 5.18 m/s
Acceleration due to gravity at 4000 km depths is :
= 3.64 m/s
Answer:
Explanation:
The work function of the metal corresponds to the minimum energy needed to extract a photoelectron from the metal. In this case, it is:
So, the energy of the incoming photon hitting on the metal must be at least equal to this value.
The energy of a photon is given by
where
h is the Planck's constant
c is the speed of light
is the wavelength of the photon
Using 
and solving for , we find the maximum wavelength of the radiation that will eject electrons from the metal:
And since
1 angstrom = 
The wavelength in angstroms is
