Mass Number
Mass Number
Mass Number: It is defined as the sum of number of protons and neutrons in the nucleus of an atom. Protons and neutrons together are called as nucleons. Mass number is denoted by A. Mass number (A) = Number of protons + number of neutrons. Eg: He, Li, At. mass = 4 and 7 for He and Li respectively.
Number of neutrons = Mass number - atomic number
Atomic number = Number of protonsMass number is written as a superscript towards the left of the symbol. In the notation for an atom, the atomic number, mass and symbol of the element are to be written as:
Here, the mass number of helium, lithium, sodium are 1, 7, 23 respectively.
Which of the following statement / statements are correct : (a) Mass number is denoted by M. (b) Number of neutrons = Mass number - atomic number (c) Mass number of lithium is 7. | |||
| Right Option : B | |||
| View Explanation | |||
The ratio between the neutrons in C and Si with respcet to atomic masses 12 and 28 is _____________ | |||
| Right Option : C | |||
| View Explanation | |||
Identify the number of neutrons present in a pair of elements with atomic numbers 20 and 13, if their mass numbers are 40 and 27, respectively: | |||
| Right Option : D | |||
| View Explanation | |||
Students / Parents Reviews [10]
My experience was very good with Abhyas academy. I am studying here from 6th class and I am satisfied by its results in my life. I improved a lot here ahead of school syllabus.
Ayan Ghosh
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Archit Segal
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Manish Kumar
10thAbout Abhyas metholodology the teachers are very nice and hardworking toward students.The Centre Head Mrs Anu Sethi is also a brilliant teacher.Abhyas has taught me how to overcome problems and has always taken my doubts and suppoeted me.
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Barkha Arora
10thOne of the best institutes to develope a child interest in studies.Provides SST and English knowledge also unlike other institutes. Teachers are co operative and friendly online tests andPPT develope practical knowledge also.
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10thI have spent a wonderful time in Abhyas academy. It has made my reasoning more apt, English more stronger and Maths an interesting subject for me. It has given me a habbit of self studying
