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प्रश्न
Differentiate mass number from atomic number.
What is the difference between atomic number and mass number?
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उत्तर
| Sr. No. | Atomic number | Mass number |
| 1. | The number of electrons or protons in an atom is called the atomic number of that atom. | The number of protons and neutrons present in its nucleus is called the mass number of that atom. |
| 2. | It is represented by the letter Z. | It is represented by the letter ‘A’. |
| 3. | Example: Helium (He) has 2 protons and two electrons; hence, its atomic number will be 2. | Example: Sodium (Na) has 11 protons and 12 neutrons; hence, its mass number A = 11 + 12 = 23 |
संबंधित प्रश्न
Fill in the blank
An ion which has a positive charge is called a ..................
Fill in the blanks.
Isotopes are the atoms of ______ element having the ______ atomic number but ______ mass number.
State the mass number, the atomic number, number of neutrons and electronic configuration of the following atoms.
`""^12""_6C, ""^16""_8O, ""^19""_9F, ""^20""_10Ne, ""_13""Al""^27, ""_17""Cl""^35`
Also, draw atomic diagrams for them.
WRITE SHORT ANSWER
Define the atomic mass number of an atom.
Fill in the following blanks :
| Atomic Number | Mass Number | Protons | Neutrons | Electrons | Symbol |
| 10 | 22 | _________ | _________ | _________ | _________ |
From the symbol `""_2^4"He"` for the element helium, write down the mass number and the atomic number of the element.
State why the atomic weight of an element is also termed relative atomic mass.
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
If an isotope of ‘H’ has mass no. = 3, how many neutrons does it have.
Elements X, Y, Z have atomic numbers 6, 9 and 12 respectively. Which one:
- forms anion – negative ion;
- forms cation – positive ion;
- has 4 electrons in the outermost orbit. [Y, Z, X]
If element M has mass number 24 and atomic number 12, how many neutrons does its atom contain?
