Chemistry
Assertion (A): The atomic mass of an element is mainly the mass of its nucleus.
Reason (R): The nucleus of an element contains neutrons and protons and the electrons have a negligible mass.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Atomic Structure
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Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Mass number of an element is the total number of protons and neutrons present in its nucleus. Hence, the asertion (A) is true.
Protons and neutrons each have a mass of about 1 atomic mass unit (amu). Electrons have a mass approximately 1/1836 that of a proton, extremely small and usually neglected in atomic mass calculations. Hence reason (R) is true and reason (R) is the correct explanation of assertion (A).
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Related Questions
An atom having mass number 13 has 7 neutrons. What is the atomic number of the atom ?
Why do and show a similar behaviour ? Atomic mass chlorine is 35.5. What is the ratio of 37Cl and 35Cl in chlorine?
Assertion (A): An alpha particle is the same as a Helium nucleus.
Reason (R): An alpha particle does not have any electron.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Isotopes of an element have similar chemical properties.
Reason (R): Isotopes of an element have the same atomic number.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.