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

The mass of electron, proton and neutron in grams are :

  1. $1.108\times 10^{-28}, 1.6726\times 10^{-24}, 1.675 \times 10^{-24}$
  2. $9.108\times 10^{28}, 1.6726\times 10^{24}, 1.675 \times 10^{24}$
  3. $9.108\times 10^{-24}, 1.6726\times 10^{-24}, 1.675 \times 10^{24}$
  4. $9.108\times 10^{-28}, 1.6726\times 10^{-24}, 1.675 \times 10^{-24}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An electron is a tiny particle with a mass of $9.108\times 10^{-28}$ g and a negative charge. All neutral atoms contain electrons. The mass of a proton is $1.6726\times 10^{-24}$ g, or about 1836 times the mass of an electron. The proton carries a positive electrical charge, that is equal in magnitude to the charge of the electron but opposite in sign. Mass of a neutron is $1.675 \times  10^{-24}$ g. It is very close to that of the proton. A neutron carries no charge.

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

Find the number of neutrons in silver having atomic mass of $107.86$.

  1. $65$
  2. $71$
  3. $61$
  4. $47$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The atomic weight is basically a measurement of the total number of particles in an atom's nucleus. Mass number can be found by rounding off an elements atomic mass to the nearest whole number.
$Mass\ Number = (Number\ of\ protons) + (Number\ of\ neutrons)$
Number of neutrons $= mass\ number- number\ of\ protons$
Atomic mass of silver $= 107.86$
Mass number $= 108$
Number of protons $= 47$
Number of neutrons $= 108 - 47$
$= 61$
$\therefore$ Number of neutrons in a silver $=61$

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

 How many moles of electron weighs one kilogram?

  1. $6.023 \times 10^{23}$
  2. $\dfrac{1}{9.108} \times 10^{32}$
  3. $\dfrac{6.023}{9.108} \times 10^{54}$
  4. $\dfrac{1}{9.108 \times 6.023} \times 10^{8}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Mass of one electron $ \displaystyle =9.108 \times 10^{-31}$ kg.

Mass of one mole of electrons $ \displaystyle =9.108 \times 10^{-31} \times 6.023 \times 10^{23}=9.108   \times 6.023 \times 10^{-8}$ kg.

The number of moles of electrons that weigh one kilogram $ \displaystyle = \dfrac {1}{9.108   \times 6.023 \times 10^{-8}}= \dfrac {1}{9.108   \times 6.023}  \times 10^{8}$

Hence, the correct option is $D$
Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

Positronium is the name given to an atom-like combination formed between_____________.

  1. a positron and a proton

  2. a positron and a neutron
  3. a positron and an $\alpha$-particle

  4. a positron and an electron
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Positronium is the name given to an atom-like combination formed between a positron and an electron. Electron  and positron are particle and antiparticle.

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

If $N _A$ is the Avogadro's number then number of valence electrons in 4.8 g of $O^{2-} $ is:

  1. $2.4\, N _A$
  2. $4.2\, N _A$
  3. $1.6\, N _A$
  4. $3.2\, N _A$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Number of mole in 4.8 gm of oxygen atom $=\dfrac{4.8}{16} = 0.3$ mole 

Number of the valence electron in one ion of $O^{2-} = 8$

Number of the valence electron in 0.3 mole of $O^{2-} = 8\times0.3\times N _A =2.4N _A$

Hence, the correct option is $(A)$.
Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

Mass of 1 mole neutrons $(m _n= 1.675 \times 10^{-27}\, kg)$ is:

  1. $1.8 \times 10^{-3}\, kg$
  2. $1.008 \times 10^{-4}\, kg$
  3. $1.08 \times 10^{-3}\, kg$
  4. $1.008 \times 10^{-3}\, kg$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass of one neutron $= 1.675 \times 10^{-27}$ kg


1 mole contains $6.02 \times 10^{23}$ neutrons

mass of 1 mole neutrons $= 1.675 \times 6.02 \times  10^{-27} \times 10^{23}$

                                         $=1.008 \times 10^{-3}$ kg

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

Select the correct statement?

  1. An atom has equal number of electrons and protons.

  2. An atom has equal number of electrons and neutrons.

  3. An atom has equal number of protons and neutrons.

  4. An atom has equal number of electrons, protons and neutrons.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An atom is electrically neutral as it has an equal number of electrons and protons, that is, an equal number of negative and positive charges. 


In order to become stable, atom loses or gains one or more electrons and forms an ion which carries a charge.

Hence the correct option is A.

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

What is the total number of electrons present in 1.6 g of methane?

  1. $6.023 \times 10^{23}$

  2. 16
  3. $12.04 \times 10^{23}$
  4. $6.023 \times 10^{24}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
1 mole methane = 16 g
Electrons in 1 mole of methane are $=6+4 \times 1=10$
Mole of methane in 1.6 g=$\cfrac{mass}{molar\ mass}$
$=\cfrac{1.6}{16}=0.1$ mole
$\therefore$ 0.1 mol methane contains $0.1 \times 10$mol electron=1 mole of electron
1 mole electron=$6.023 \times 10^{23}$ electrons
Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

The molar mass of an electron is:

  1. $6.023\times10^{23}$ g/mol
  2. $5.486\times10^{-4}$ g/mol
  3. $9.108\times10^{-28}$ kg/mol
  4. $9.108\times10^{-24}$ g/mol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mass of an electron $=9.1\times 10^{-28}$g
1 mole $=6.02\times 10^{23}$ electrons
$\therefore$ molar mass of electron $=(9.1\times 10^{-28}) \times (6.02\times 10^{23}) = 5.48\times 10^{-4}$ g/mole

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

The total number of electrons present in 1.8 g of water is :

  1. $6.023\times 10^{22}$
  2. $10.8576\times 10^{23}$
  3. $10.8576\times 10^{22}$
  4. $6.023\times 10^{23}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

We know that, 1 molecule of water consists of 10 electrons (2 electrons each of two hydrogen atoms and 8 electrons of one oxygen atom).
The number of molecules present in 1.8 g of water.
$18 : g : of : H _2O\xrightarrow[]{contains}6.023\times 10^{23}molecules$
$\Rightarrow1.8 : g : of : H _2O : contains : '! x' : molecules$
$x=\dfrac{1.8\times 6.023\times 10^{23}}{18}$
$=\dfrac{ 6.023\times 10^{23}}{10}=6.023\times 10^{22}molecules$.
$\therefore$ Number of electrons in 1.8 g of water $=6.023\times 10^{22}\times10=6.023\times 10^{23}$