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Proton, Electron, Neutron - Number Calculation

Q: Which of the following statements is false?

The e/m value of electron is approximately \$1837\$ times e/m value of proton, hence e/m value of proton is not highest. Thus the false statement is present in option C. Thus answer is option C.

Q: If \$N_{A}\$ is Avogadro's number, then number of valence electrons in 4.2 g of nitride ion \$\left ( N^{3-} \right )\$ is:

Number of moles \$=\dfrac { 4.2 }{ 14 } =0.3\$ mol\$0.3\$ mol \$=0.3\times { N }_{ A }\$ ions.\$\Rightarrow 8\times 0.3\times { N }_{ A }\$ electrons (as each ion contains \$5+3={ 8e }^{ - }\$)\$\Rightarrow 2.4{ N }_{ A }\$ electronsHence, the correct option is A.

Q: (i) Calculate the number of electrons which will together weighs one gram. (ii) Calculate the mass and charge of one mole of electrons.

The number of electrons which will weigh 1 g is \$\displaystyle \frac {10^{-3}}{9.11 \times 10^{-31}} = 1.098 \times 10^{27} \$ .Mass of one mole of electrons is \$\displaystyle 9.11 \times 10^{-31} \times 6.023 \times 10^{23}= 5.486 \times 10^{-7} \$kg.Charge of 1 mole of electrons is \$\displaystyle 1.602 \times 10^{-19} \times 6.023\times 10^{23} = 9.647\times 10^{4}\ C\$.

Q: An element with mass number \$81\$ contains \$31.7\%\$ more neutrons as compared to protons. Assign the atomic symbol.

Let \$x\$ be the number of protons. The number of neutrons is \$\displaystyle x+0.317x=1.317x\$. The mass number is \$81\$. It is equal to the sum of the number of protons and the number of neutrons.\$\displaystyle 81 = x +1.317 x =2.317x \$\$\displaystyle x = 35 \$Hence, the symbol is \$\displaystyle _{35}^{81}Br \$.

Q: Sum of number of protons, electrons, and neutron in 12g of \${}_6^{12}C\$ is:

The atomic weight of carbon = 12 g and the given weight = 12 gAs we know that, \$\text{No. of moles} = \cfrac{\text{Given weight}}{\text{Molecular weight}}\$\$\therefore\$ No. of moles of Carbon in 12 g \$= \cfrac{12}{12} = 1 \text{ mole}\$No. of atoms present in 1 mole of Carbon \$= {N}_{A} = 6.023 \times {10}^{23}\$As 1 mole of carbon contains 6 electrons, 6 protons and 6 neutrons.\$\therefore \text{ No. of electrons in }6.023 \times {10}^{23} \text{ atoms of carbon} = 6 \times 6.023 \times {10}^{23}\$Similarly,\$\text{No. of protons in }6.023 \times {10}^{23} \text{ atoms of carbon} = 6 \times 6.023 \times {10}^{23}\$\$\text{No. of neutrons in }6.023 \times {10}^{23} \text{ atoms of carbon} = 6 \times 6.023 \times {10}^{23}\$\$\therefore\$ Sum of electrons, protons and neutrons in 12g of carbon = no. of electrons in 12 g carbon + no. of protons in 12 g carbon + no. of neutrons in 12 g carbon\$ = 6 \times 6.023 \times {10}^{23} + 6 \times 6.023 \times {10}^{23} + 6 \times 6.023 \times {10}^{23}\$\$= 108.414 \times {10}^{23} = 1.084 \times {10}^{25}\$So, the correct option is \$C\$

Q: Number of neutrons present in \$1.7\$ g of ammonia is:

Let us consider the problem.For, moles of \$N{H_3} = \frac{{1.7}}{{17}} = 0.1\$Let the Neutrons in 1 molecules of \$N{H_3} = 7 + 3 \times 0 = 7\$Hence,Number of Neurons \$= 0.1 \times {N_A} \times 7\$The correct answer is \$0.7{N_A}\$

Q: Calculate number of neutrons present in \$12 \times 10^{25}\$ atoms of oxygen \$(_8O^{17})\$: (Given : N\$_A = 6 \times 10^{23}\$)

Atomic number =\$ P =8\$ Atomic Mass =\$ N+P=17\$ \$N=9\$ Total no. of Neutrons = \$9\times 12\times 10^{25}\$ =\$\dfrac{9\times 12\times 10^{25}\times N_{A}}{6\times 10^{23}}\$ \$=1800N_{A}\$Hence, the correct option is C.

Q: The mass of \$1\$ mole electron is \$0.55mg\$.

Mass of one electron is \$9.1 \times 10^{-28}gm\$So mass of one mole of electronis \$ ( 6.02 \times 10^{23} )\times ( 9.1 \times 10^{-28} )\$= \$0.55 \times 10^{-3}\$ gm \$=0.55mg\$ So, the given statement is true.

Q: The order (lowest to highest) of e/m (charge/mass) ratio for electron (e), proton (p), neutron (n) and alpha particle \$(\alpha)\$ is:

The increasing order (lowest to highest) of e/m (charge/mass) ratio is \$ n < \alpha < p < e\$.Neutron being neutral has zero charges and lowest e/m ratio. An electron has a unit charge but negligible mass. Hence, the electron has a maximum e/m ratio.For an alpha particle, the e/m ratio is 2/4 or 0.5.For proton, e/m ratio is 1/1 or 1.

Q: The total number of neutrons present in 54 mL \$ H_{2}O (l) \$ are:

Molecular weight of \$H_2O=18g\$No. of neutrons in \$1\$ mole i.e. \$18g\$ of \$H_2O=8N_A\$ ( from \$O\$ atom, as \$H\$ has no neutron)Given moles of \$H_2O=\cfrac{54}{18}=3\$\$\therefore\$ Total no. of neutrons present \$=3\times 8N_A=24N_A\$

Chemistry

definition

Find the number of electron, protons and neutrons using atomic and mass number

Atomic number represent number of protons or electrons and Mass number represent total of protons + neutrons.
For example, Consider N(nitrogen) with atomic number 7 and mass number 14. As atomic number represent number of proton or electron, hence, nitrogen contain 7 proton and 7 neutron and Mass number is 14 out of which 7 are proton, so remaining 7 are neutrons.

formula

Number of sub-atomic particles in an element

Number of protons

=

number of electrons

=

Atomic number
Number of neutrons

=

Atomic mass

-

atomic number

REVISE WITH CONCEPTS

View solution

The total number of neutrons present in 54 mL $H_{2} O (l)$ are:

Medium

View solution

definition

Find the number of electron, protons and neutrons using atomic and mass number

formula

Number of sub-atomic particles in an element

REVISE WITH CONCEPTS

Subatomic Particles - Electron

Reason Behind Discovery of Electron

Subatomic Particles - Protons

Discovery of Neutrons

Subatomic Particles - Comparison

Quick Summary With Stories

Calculation of Number of Sub-Atomic Particles

Which of the following statements is false?

If NA​ is Avogadro's number, then number of valence electrons in 4.2 g of nitride ion (N3−) is:

(i) Calculate the number of electrons which will together weighs one gram. (ii) Calculate the mass and charge of one mole of electrons.

An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.

Sum of number of protons, electrons, and neutron in 12g of 612​C is:

Number of neutrons present in 1.7 g of ammonia is:

Calculate number of neutrons present in 12×1025 atoms of oxygen (8​O17): (Given : NA​=6×1023)

The mass of 1 mole electron is 0.55mg.

The order (lowest to highest) of e/m (charge/mass) ratio for electron (e), proton (p), neutron (n) and alpha particle (α) is:

The total number of neutrons present in 54 mL H2​O(l) are:

If $N_{A}$ is Avogadro's number, then number of valence electrons in 4.2 g of nitride ion $(N^{3 -})$ is:

(i) Calculate the number of electrons which will together weighs one gram.
(ii) Calculate the mass and charge of one mole of electrons.

An element with mass number $81$ contains $31.7 %$ more neutrons as compared to protons. Assign the atomic symbol.

Sum of number of protons, electrons, and neutron in 12g of $_{6}^{12} C$ is:

Number of neutrons present in $1.7$ g of ammonia is:

Calculate number of neutrons present in $12 \times 1 0^{25}$ atoms of oxygen $(_{8} O^{17})$ :
(Given : N $_{A} = 6 \times 1 0^{23}$ )

The mass of $1$ mole electron is $0.55 m g$ .

The order (lowest to highest) of e/m (charge/mass) ratio for electron (e), proton (p), neutron (n) and alpha particle $(α)$ is:

The total number of neutrons present in 54 mL $H_{2} O (l)$ are: