Answer;
D. carbon-12 atom
Explanation;
-One atomic mass unit is the mass that is exactly equal to one-twelfth the mass of one carbon-12 atom. Therefore, the mass of carbon-12 is 12 amu and this provides the standard that is used in measuring the atomic mass of all other elements.
-The atomic mass of carbon is 12.01 and not 12.00 in the periodic table.
-Due to the fact that there are more than one element for most naturally occurring elements, the average mass of the naturally occurring mixture of isotopes is taken while determining the atomic mass of an element.
Answer:
energy
Explanation:
The photon of light that is emitted as an electron drops back to its original orbit is energy and this energy is released during de-excitation process.
The electron is jumped into higher level and back into lower level by absorbing and releasing the energy.
The process is called excitation and de-excitation.
Excitation:
When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits. For example if electron jumped from K to L it must absorbed the energy which is equal the energy difference of these two level. The excited electron thus move back to lower energy level which is K by releasing the energy because electron can not stay longer in higher energy level and comes to ground state.
De-excitation:
When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum
Answer:
There is 5.56 g of gold for every 1 g of chlorine
Explanation:
The ratio is the relationship between two numbers, defined as the ratio of one number to the other. So, the ratio between two numbers a and b is the fraction 
You know that a compound has 15.39 g of gold for every 2.77 g of chlorine. This can be expressed by the ratio:

The proportion is the equal relationship that exists between two reasons and is represented by: 
This reads a is a b as c is a d.
To calculate the amount of gold per 1 g of chlorine, the following proportion is expressed:

Solving for the mass of gold gives:

mass of gold= 5.56 grams
So, <u><em>there is 5.56 g of gold for every 1 g of chlorine</em></u>
Answer:
0.23
Explanation:
- It is known that, the mass to mass ratio of the salt to water
= (mass of salt / mass of water)
= (25.0 g / 105.0 g)
= 0.23
D) refracted
because , the light changes direction.. causing the penny to look bigger than it is.