$(A)$ The ion $X^{2-}$ has $10$ electrons, which means it has gained $2$ electrons to form the ion.Therefore, the number of protons in the neutral ato

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Atomic number $= 8$, Mass number $= 16$

$(A)$ The ion $X^{2-}$ has $10$ electrons, which means it has gained $2$ electrons to form the ion.Therefore, the number of protons in the neutral atom $X$ is $10 - 2 = 8$.Atomic number is equal to the number of protons, so the atomic number of $X$ is $8$.Mass number is the sum of protons and neutrons.Mass number $= \text{Number of protons} + \text{Number of neutrons} = 8 + 8 = 16$.

Class 9 Science STRUCTURE OF THE ATOM Mix Example - STRUCTURE OF THE ATOM

Easy

An ion $X^{2-}$ contains $10$ electrons and $8$ neutrons. What are the atomic number and mass number of element $X$?

A
Atomic number $= 8$, Mass number $= 16$
B
Atomic number $= 10$, Mass number $= 18$
C
Atomic number $= 8$, Mass number $= 18$
D
Atomic number $= 10$, Mass number $= 16$

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STRUCTURE OF THE ATOM

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Mix Example - STRUCTURE OF THE ATOM

Explain the following with one example of each:
$(i)$ Atomic number
$(ii)$ Mass number

Easy

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An atom of an element $X$ may be written as ${ }_{4}^{9} X$.
$(a)$ What does the figure $9$ indicate?
$(b)$ How many neutrons does this element $X$ contain?

Medium

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The atomic numbers of calcium and argon are $20$ and $18$ respectively,but the mass number of both these elements is $40$. What is the name given to such a pair of elements?

Medium

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State whether the following statement is true or false:
An atom of each element has a definite combining capacity,called its valency.

Easy

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The average atomic mass of a sample of an element $y$ is $35.5 \,u$. What are the percentages of isotopes $_{17}^{37}y$ and $_{17}^{35}y$ in the sample?

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An ion $X^{2-}$ contains $10$ electrons and $8$ neutrons. What are the atomic number and mass number of element $X$?

Similar Questions

Explain the following with one example of each:$(i)$ Atomic number$(ii)$ Mass number

An atom of an element $X$ may be written as ${ }_{4}^{9} X$.$(a)$ What does the figure $9$ indicate?$(b)$ How many neutrons does this element $X$ contain?

The atomic numbers of calcium and argon are $20$ and $18$ respectively,but the mass number of both these elements is $40$. What is the name given to such a pair of elements?

State whether the following statement is true or false:An atom of each element has a definite combining capacity,called its valency.

The average atomic mass of a sample of an element $y$ is $35.5 \,u$. What are the percentages of isotopes $_{17}^{37}y$ and $_{17}^{35}y$ in the sample?

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Explain the following with one example of each:
$(i)$ Atomic number
$(ii)$ Mass number

An atom of an element $X$ may be written as ${ }_{4}^{9} X$.
$(a)$ What does the figure $9$ indicate?
$(b)$ How many neutrons does this element $X$ contain?

State whether the following statement is true or false:
An atom of each element has a definite combining capacity,called its valency.