Answer:
Explanation:
The speed of light (electromagnetic wave) is given by the following formula:
(1)
Where:
is the speed of light
the frequency
the wavelength
So, we have to find from (1):
(2)
<u>Finally:</u>
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Knowing 
Answer:
A). A Lever and Wheel and Axle.
Explanation:
1. A wheel axle is most obvious, as the wheels are connected via a chain and axle with spokes. This helps keep the wheels moving forward with less effort than walking.
2. A Lever is used to help Balance you as you ride the bike. Without it, you would tip over, and lose all the momentum you had gained up until that point.
3. (I took the test on e2020)
Answer:
Protons = 50
Mass number = 119
Explanation:
A neutral of tin, Sn, has a Z value of 50 and neutrons are 69.
Z is the atomic number. The atomic number is equal to number of protons or number of electrons in an atom that is neutral i.e:
Z = PROTONS = ELECTRONS
So the number of protons = 50 since Z is 50
>>>>>>>>>>>>>>>¦
The bulk of the mass of an atom is concentrated in the nucleus. To calculate mass number, we simply sum all the elementary particles in the nucleus i.e protons and neutrons. These particles are called the nucleons.
Mass number (A) = P + N
= 50 + 69
= 119
Answer : The energy released in first step of thorium-232 decay chain is 
Explanation :
First we have to calculate the mass defect 
.
The balanced reaction is,
Mass defect = Sum of mass of product - sum of mass of reactants
conversion used : 
Now we have to calculate the energy released.
The energy released is
Therefore, the energy released in first step of thorium-232 decay chain is
