Tag: atom

Quizzes (5) Questions (42)

Questions Related to atom

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

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

  1. Proton

  2. Neutron

  3. Electron

  4. Isotope

  5. Ion
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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)

  1. 7 : 3

  2. 3 : 7

  3. 1 : 2

  4. 2 : 1
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $= 7:14 = 1:2$

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

The ratio of mass of proton to electron is about:

  1. $1.8\times 10^{-3}$
  2. $1.8\times 10^{3}$

  3. 1

  4. 0
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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

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

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

  1. 30

  2. 32

  3. 34

  4. 42
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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 $=6.0\times 10^{23}$)

  1. $5.33\times 10^{-3}g$
  2. $5.35\times 10^{-23}g$
  3. $5.33\times 10^{-43}g$
  4. $32\times 10^{3}g$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. $6.85\times {10}^{22}$
  2. $7.50\times {10}^{23}$
  3. $1.5\times {10}^{23}$
  4. $1.8\times {10}^{22}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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