Tag: the structure of atoms

Questions Related to the structure of atoms

Which of the following has negligible weight as compared to others?

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. Proton

  2. Neutron

  3. Electron

  4. Isotope

  5. Hydrogen ion

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Correct Option: C
Explanation:

Option $C$ is the correct answer.

Mass of an electron is very negligible. It is $ {9.1}{\times}{10}^{-31} $ Kg.

Which of the following is neutral and weighs 1 amu?

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. Proton

  2. Neutron

  3. Electron

  4. Isotope

  5. Ion

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Correct Option: B
Explanation:

A neutron is electrically neutral particle. And its mass is 1 amu or $ {1.67} $ $ {\times} $ $ {10}^{-27} $ Kg

Thus, option $B$ is the correct answer.

Which of the following has negative charge and is present in atom as pairs with opposite spin?

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. Proton

  2. Neutron

  3. Electron

  4. Isotope

  5. Ion

Show answer
Correct Option: C
Explanation:

Option $C$ is the correct answer.

An electron is a negatively charged particle. In an orbital, if two electrons are present together, they should and must have opposite spins. Because, no two electrons can be identically same.

If two atoms are isotopes, in what characteristic do they differ? 

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. Number of protons

  2. Number of neutrons

  3. Number of electrons

  4. Atomic number

  5. Electronic charge

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Correct Option: B
Explanation:

Isotopes are atoms with the same number of protons but that have a different number of neutrons.

The ratio of the neutrons present in nitrogen atom and a silicon atom is: 

(Mass number of nitrogen and silicon is 14 and 28 respectively)

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. 7 : 3

  2. 3 : 7

  3. 1 : 2

  4. 2 : 1

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Correct Option: C
Explanation:

For nitrogen; atomic number = 7 and mass number = 14 

$\therefore$ Number of neutrons $= 14-7 = 7$
For silicon; atomic number = 14 and mass number = 28 
$\therefore$ number of neutrons $= 28-14= 14$
$\therefore$ Ratio of number of neutrons in nitrogen and silicon $= 7:14 = 1:2$

Though the three fundamental particles are present in almost all elements, one element does not have one of them. Identify the particle

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. neutron

  2. proton

  3. electron

  4. nucleons

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Correct Option: A
Explanation:

Neutron is not present in hydrogen. Electronic configuration of hydrogen is 1 $( _1H^1)$.

The ratio of mass of proton to electron is about:

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. $1.8\times 10^{-3}$

  2. $1.8\times 10^{3}$

  3. 1

  4. 0

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Correct Option: B
Explanation:

Mass of proton = $1.6\times 10^{-27}$kg and mass of electron = $9.1\times 10^{-31}$kg
$\therefore\dfrac{\text{mass of proton}}{\text{mass of electron}} = \dfrac{1.6\times 10^{-27}}{9.1\times 10^{-31}} = 1.8\times 10^{3}$

The electronic configuration of an ion $M^{2+}$ is 2, 8, 14. If its mass 56, the number of neutrons in its nucleus is :

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. 30

  2. 32

  3. 34

  4. 42

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Correct Option: A
Explanation:

$M^{2+}=2, 8, 14;\Rightarrow $ Electronic Configuration of $M=2, 8, 16$
So. total electrons in M will be $=26$
i.e., atomic number $(Z)=26$, Mass number (given) $=56$
$\therefore$ Number of neutrons$=A-Z=56-26=30$

Hence, the correct option is A.

Suppose the chemists hed selected $10^{20}$ as the number of particles in a mole. The molar mass of oxygen gas would be (Use Avogadro number $=6.0\times 10^{23}$)

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. $5.33\times 10^{-3}g$

  2. $5.35\times 10^{-23}g$

  3. $5.33\times 10^{-43}g$

  4. $32\times 10^{3}g$

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Correct Option: A
Explanation:

Molar mass of oxygen we know is $32$g.

$\therefore 1$ molecule oxygen weighs $\cfrac { 32 }{ 6\times { 10 }^{ 23 } } $g
$\Rightarrow { 10 }^{ 20 }$ molecules would weigh $\cfrac { 32 }{ 6\times { 10 }^{ 23 } } \times { 10 }^{ 20 }$
$\therefore 1 $mole would weigh $=5.33\times { 10 }^{ -3 }$g.

The number of electrons present in $100ml$ of $0.1N$ ${H} _{2}{SO} _{4}$ is:

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. $6.85\times {10}^{22}$

  2. $7.50\times {10}^{23}$

  3. $1.5\times {10}^{23}$

  4. $1.8\times {10}^{22}$

Show answer
Correct Option: C
Explanation:

Normality=$n\times Molarity$

$\therefore 0.1=2\times \cfrac { moles\quad  of\quad  H _2SO _4}{ 0.1 }$
$\therefore Moles\quad  of\quad  H _2SO _4=0.005\quad moles$

$1$ molecule of $H _2SO _4$ contains $50$ electrons.

No. of molecules in $0.005$ moles=$0.005\times6.022\times {10}^{ 23 }$
=$0.03011\times {10}^{ 23 }$ molecules

$\therefore$ No. of electrons in $0.005$ moles=$0.03011\times {10}^{ 23 }\times 50$
=$1.5\times {10}^{ 23 }$ electrons