Single Choice

An element with mass number 81 contains 31.7% more neutrons as compared to protons. Find the symbol of the atom.

A$$^{81}_{34}Se$$
B$$^{81}_{35}Br$$
Correct Answer
C$$^{81}_{36}Kr$$
D$$^{81}_{37}Rb$$

Solution

Mass number of the element =81
i.e. $$p+n=81$$
Let the number of protons be x.

Number of neutrons = $$x+\cfrac{31.7}{100}\times x= 1.317x$$

$$\therefore x+1.317x =81$$ or $$2.317x = 81$$

or $$x= \cfrac{81}{2.317} = 35$$

Symbol of the element = $$^{81}_{35}Br$$

SIMILAR QUESTIONS

Atomic Structure

How many neutrons are there in $$^{88}_{38}Sr$$?

Atomic Structure

Compute the difference in masses of $$10^{3}$$ moles each of magnesium atoms and magnesium ions. (Mass of an electron $$= 9.1\times 10^{-31} \ kg) $$

Atomic Structure

Compare an electron and a proton in respect of mass and charge.

Atomic Structure

Compare a proton and a neutron in respect of mass and charge.

Atomic Structure

How does an electron differ from a neutron?

Atomic Structure

Fill the following blanks: Atomic number Mass number protons neutrons electrons symbol 10 22 ......... .......... .......... .........

Atomic Structure

Fill in the following blanks in respect of an atom of an element. No: of protons No: of neutrons Mass number Atomic number No: of electrons symbol 11 12 ............ ............ ............ .........

Atomic Structure

Complete the table given below by identifying $$P,Q$$ and $$R$$. Element Symbol No of Protons No of Neutrons No of Electrons Sodium $$^{23}_{11}Na$$ $$11$$ $$P$$ $$11$$ Chloride $$^{35}_{17}Cl$$ $$Q$$ $$18$$ $$17$$ Uranium $$R$$ $$92$$ $$146$$ $$92$$ $$S$$ $$^{19}_9F$$ $$9$$ $$10$$ $$9$$

Atomic Structure

The atom of element is made up of $$4$$ protons $$5$$ neutrons and $$4$$ electrons. What are its atomic number and the number?

Atomic Structure

A species having only one electron has ionization energy of $$11810\quad { mol }^{ -1 }$$. The number of protons in its nucleus will be:

Contact Details