Answer:
A) 20
B) 40
C) Ca
D) 10
E) 9
F) F
Explanation:
The MASS NUMBER is the number of protons + the number of neutrons.
The ATOMIC NUMBER is the number of protons.
You can take the MASS NUMBER - ATOMIC NUMBER = NUMBER OF NEUTRONS.
Each element is unique and distinguished by the NUMBER OF PROTONS = ATOMIC NUMBER, ie...the number of protons in its nucleus. You can find the element's name and symbol on the Periodic Table.
<h3>
Answer:</h3>
7.226 × 10^23 molecules.
<h3>
Explanation:</h3>
- A compound is a substance that is made by two or more atoms from different elements.
- A mole of a compound contains a number of molecules equivalent to Avogadro's number, 6.022 × 10^23.
- That is, one mole of a compound contains 6.022 × 10^23 molecules.
In this case we are given;
Number of moles of H₂O as 1.2 moles
But, 1 mole of H₂O contains 6.022 × 10^23 molecules.
We are required to calculate the number of molecules present;
- To calculate the number of molecules we are going to multiply the number of molecules in one mole by the number of moles.
Number of molecules = 1.2 moles × 6.022 × 10^23 molecules/mole
= 7.226 × 10^23 molecules.
Thus, 1.2 moles of water contains 7.226 × 10^23 molecules.
<u>Answer:</u> The correct answer is isotopes generally have the same chemical properties, but often different nuclear properties.
<u>Explanation:</u>
Isotopes are defined as the chemical species of the same element which have same atomic number but differ in their mass number.
Atomic number is defined as the number of protons or electrons that are present in a neutral atom.
Atomic number = number of protons = number of electrons
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
Nuclear properties of an element is determined by the number of protons and neutrons present in a nucleus.
Chemical properties of an element is determined by the number of electrons present in an atom.
Isotopes have same atomic number, this means that they have same number of protons and electrons but they differ in mass number, which means that they differ in number of neutrons.
Hence, isotopes will have same chemical properties but different nuclear properties.
Answer:
The emission spectrum lines are the changes in the quantum energy levels of the single electron in the Hydrogen atom.
Explanation:
Electrons move around the hydrogen atom in electron waves patterns. These waves occur in distinct quantum energy levels.
The change from one quantum energy level to another energy level has a definite energy level change. There is a wave length associated with each change in energy levels. These wave lengths have a color associated with them.
Low energy level changes have long wave lengths associated with them giving red and orange colors.
High energy level changes have short wave lengths associated with them giving blue and violet colors.
Note each atom has a unique emission spectrum associated with the energy levels and electron structure of the atom. Helium was first discovered by looking at its emission spectrum as seen in the sun.
Explanation:
The equation of the reaction is:
Na2CO3 + AgNO3 → NaNO3 + Ag2CO3
but this equation, not a balanced equation so let's make it a balanced equation:
- we will start with Na number of atoms, we should make the Na atom number is equal on both sides.So we put 2 NaNO3 instead of NaNO3
- and then the Ag atom, we put 2AgNO3 instead of AgNO3 to make the number of Ag on each side are equals.
So the final balanced equation for this reaction is:
Na2CO3(aq) + 2AgNO3(aq) → 2NaNO3(aq) + Ag2CO3(s)
SO know we have number of Na on each side = 2
number of Ag on each side = 2
