MCQ Questions for Class 11 Medical Chemistry Structure Of Atom Quiz 4

How will you find out the maximum number of electrons in the main energy level?

0%
$n$
0%
$n^2$
0%
$2n^4$
0%
$2n^2$

Explanation

The maximum number of electrons in an energy level is given by

$2\left( { n }^{ 2 } \right)$ . Here n is the principle quantum number of the energy level. Thus we have

$2\left( { 1 }^{ 2 } \right) =2$ electrons in first orbit and

$8$ in second orbit and so on.

Atomic number of Radon is:

0%
54
0%
86
0%
72
0%
68

Explanation

The number of protons found in the nucleus of an atom of a given element is called atomic number. Elements are placed in periodic tablee according to their atomic number.

Example:-

(1) Atomic number of Radon is

$86$

$^{222}_{86}R$

(2) Atomic number of Bromine is

$35$

$^{79.9}_{35}Br$

A fine spectrum is splitting of a spectrum into closely spaced lines.

0%
True
0%
False

Which of the following statements is false?

0%
Bohr's theory explains only the spectra of single electron species.
0%
The energy of an electron remains constant during electronic transition.
0%
The angular momentum of an electron is quantised.
0%
According to Bohr's theory, electrons revolve around the nucleus in circular orbits.

The atomic number of magnesium isThe number of protons in the nucleus of magnesium atom is:

0%
6
0%
10
0%
12
0%
24

Explanation

For Mg atom the atomic number,

$Z = 12$

Number of protons in the nucleus

$=$ Atomic number of an atom

$= 12$

Hence option C is correct.

According to Bohr's atomic model, electrons revolve around the nucleus in stationary orbits.

0%
True
0%
False

The electrons revolve around the nucleus only in certain fixed paths called:

0%
orbits
0%
orbitals
0%
center
0%
layer

Explanation

The electrons revolve around the nucleus only in certain fixed paths called orbits. They are K, L, M, N, etc. Each orbit consists of a fixed number of electrons. The electrons are distributed in the orbits according to the formula

$2n^2$ .

The ratio of mass of proton to electron is about:

0%
$1.8\times 10^{-3}$
0%
$1.8\times 10^{3}$
0%
1
0%
0

Explanation

Mass of proton =

$1.6\times 10^{-27}$ kg and mass of electron =

$9.1\times 10^{-31}$ kg

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

Isotopes has different:

0%
physical properties
0%
chemical properties
0%
atomic number
0%
mass number

Atoms of two elements P and Q have 5 electrons in

$2^{nd}$ shell and

$3^{rd}$ shell respectively. What will be the atomic numbers of these elements?

0%
4 : 15
0%
5 : 15
0%
7 : 13
0%
7 : 15

Explanation

P has

$5$ electrons in the second shell (

$n = 2$ ) , thus the electronic configuration is:

$2,5$ and atomic no.

$= 7$
Q has

$5$ electrons in the third shell (

$n = 3$ ) , thus the electronic configuration is:

$2,8,5$ and atomic no.

$= 15$ .

The first use of quantum theory to explain the structure of atom was made by:

0%
Heisenberg
0%
Bohr
0%
Planck
0%
Einstein

Explanation

It was in

$1913$ that Neils Bohr put forth the stability of the atom and with the help of Planck's quantum theory explain the reason for spectral lines. Bohr first made use of quantum theory to explain the structure of atoms and proposed that the energy of electrons in an atom is quantized.

Which of the following is true when Bohr gave his model for hydrogen atom?

0%
It was not known that hydrogen lines could be explained as differences of terms like $R/n^2$ with $R$ being a constant and $n$ an integer
0%
It was not known that positive charge is concentrated in a nucleus of small size
0%
It was known that radiant energy occurred in energy bundles defined by $hv$ with $h$ being a constant and $v$ a frequency
0%
Bohr knew terms like $R/n^2$ and in the process of choosing allowed the orbits to fit them, he got angular momentum = $nh/2\pi$ as deduction

In Bohr's model of hydrogen atom,

0%
The radius of $nth$ orbit is proportional to $n^2$
0%
The total energy of electron in $n^{th}$ orbit is proportional to $n$
0%
The angular momentum of the electron in an orbit is an integral multiple of $h/2\pi$
0%
The magnitude of the potential energy of electron in any orbit is greater than its Kinetic energy

Explanation

The expression of radius of n th orbit for H-atom:

$r_n=\dfrac{n^2h^2}{4\pi^2e^2mk}$ where

$k=1/4\pi\epsilon_0$

so,

$r_n\propto n^2$

The KE of electron for H-atom is

$K_n=\dfrac{ke^2}{2r_n}$ or potential energy,

$U_n=-\dfrac{ke^2}{r_n}$

Total energy

$E=K_n+U_n=-\dfrac{ke^2}{2r_n}$ so

$E \propto 1/r_n=1/n^2$

Also

$|U_n|>K_n$

From Bohr's second postulate, angular momentum,

$L=mvr=nh/2\pi$

Two isotopes of an element X are present in the ratio of 1:2, having mass number M and (M+0.5) respectively. Find the mean mass number of X.

0%
$M+\cfrac { 2 }{ 3 }$
0%
$M+\cfrac { 1 }{ 3 }$
0%
$M+\cfrac { 1 }{ 4 }$
0%
$M+3$

Explanation

Mean Mass number is the average mass of all isotopes.

So, Mean Mass Number

$= \dfrac { 1\times M\ +(M+0.5)\times 2 }{ 1+2 } = M+\dfrac { 1 }{ 3 }$

Following are the p-block elements.

Atomic numbers :

$Ge$ = 32 ,

$As$ = 33 ,

$Se$ = 34

Which of the these elements belong to

$14^{th}$ group and

$4^{th}$ period?

0%
$Ge$
0%
$As$
0%
$Se$
0%
None of the above

Explanation

Elements	Electronic Configuration	Block	Group	Period
$Ge$ (32)	$[Ar]\ 3d^{10}\ 4s^2\ 4p^2$	d	14	4
$As$ (33)	$[Ar]\ 3d^{10}\ 4s^2\ 4p^3$	d	15	4
$Se$ (34)	$[Ar]\ 3d^{10}\ 4s^2\ 4p^4$	d	16	4

Two electrons occupying the same orbital are distinguished by:

0%
Principle quantum Number
0%
Magnetic quantum number
0%
Azimuthal quantum number
0%
Spin quantum number

Impossible orbital among the following is

0%
$3f$
0%
$2p$
0%
$4d$
0%
$2s$

Explanation

If the value of principle quantum number is 3. So the maximum possible value of Azimuthal quantum number is (3-1)=2 which describes the d subshell. But for f subshell, the value of

$l$ must be 3. So, 3f orbital is not possible at all.

When

$Z$ is doubled in an atom, which of the following statement is consistent with Bohr's theory?

0%
Energy of a state is doubled
0%
Radius of an orbit is doubled
0%
Velocity of electrons in the orbit is doubled
0%
Radius of an orbit is quadrupled.

Explanation

Let the initial charge be

$z$ .

$\dfrac{kz^2}{r^2}=\dfrac{m_ev^2}{r}$

when

$z$ is doubled,

$\dfrac{k{(2 z)}^2}{r^2}=\dfrac{m_e(v_1)^2}{r}$

$v_1=2v$

Which of the following isotopes is likely to be most stable?

0%
$_{30}^{71}\textrm{Zn}$
0%
$_{30}^{66}\textrm{Zn}$
0%
$_{30}^{64}\textrm{Zn}$
0%
none of these

Explanation

In any atom, protons and neutrons are packed together in a very small space in the nucleus.

There must be some force of attraction between these particles to maintain the existence of nucleus.
The columbic force of attraction is not enough to hold many particles in such a small space, as the repulsion force between protons would render the nucleus highly unstable and tend to disintegration.
Hence, the force of attraction between nucleons which is stronger than the repulsive force between protons is called as nuclear forces.
Nuclear forces operate within a small distance around 0.10 fermi only.

Those nucleus with n/p ratio one is highly stable. Elements with high n/p ratio are unstable an radioactive in nature. Elements till atomic number 20 are stable with n/p =1, as atomic number increases, n/p ratio increases and instability increases.
Here, n/p ratio of all nuclei is

$_{30}^{71}\textrm{Zn}$

$n/p = 41/30$

$_{30}^{66}\textrm{Zn}$

$n/p = 36/30$

$_{30}^{64}\textrm{Zn}$

$n/p = 34/30$
so nuclei with minimum n/p ratio is most stable.

J.J.Thomson for the first time identified an electron as a particle and his son G.P.Thomson first time identified an electron as a wave and both were awarded Nobel prizes in different years.

0%
True
0%
False

Explanation

George Paget Thomson (G.P.Thomson) awarded Nobel Prize in

$1937$ "for their experimental discovery of the diffraction of electrons by crystals and first time identified electron as a wave" and his father Joseph John Thomson was awarded Nobel Prize in

$1906$ "for the first time identified electron as a particle".
Therefore, the given statement is true.

State True or False.

$\alpha$ -particle, when passed through gases, cause large ionisation.

0%
True
0%
False

State True or False.

The properties of elements are periodic function of their atomic number.

0%
True
0%
False

State whether the given statement is true or false :

Elements with an odd number of protons usually have only one or two stable isotopes.

0%
True
0%
False

State True or False.

$H^2$ is more reactive than

$H^1$ .

0%
True
0%
False

Explanation

The chemical reactivities of

$^1H$ and

$^2H$ are identical as they are related to the electronic configuration.

The number of electrons in a neutral atom is equal to:

0%
atomic mass number
0%
number of neutrons
0%
its valency
0%
number of protons

State True or False.

Solutions of Schrodinger equation for

$H$ -atom give the same set of values of the energy levels as does the Bohr's theory.

0%
True
0%
False

What is the difference in number of neutrons in Protium and Deuterium?

0%
1
0%
2
0%
3
0%
4

Explanation

Isotopes of an element differ in the number of neutrons in their nuclei.
They have the same number of protons and electrons. Hence the same atomic number but a different mass number.

Protium and Deuterium,

$_1^1H$ and

$_1^2H$ , have the same atomic number and different mass number. They have 1 proton and 1 electron each. But they have 0 and 1 neutrons respectively.

So, the difference in the number of neutrons

$=1$ .

Matter is composed of:

0%
atoms
0%
molecules
0%
tiny particles
0%
all of the above

In the nuclear reaction

$H^2+H^2\rightarrow He^3 +X,$

$X$ stands for:

0%
$_{+1}{e^{0}}$
0%
$_0{n^{1}}$
0%
$_{-1}{e^{0}}$
0%
$H^1$

Explanation

The given equation or reaction represents the nuclear fusion reaction

$_1H^2 +_1H^2\rightarrow He^3+ _on^1+hv$

Hence,

$X$ stands for

$_on^1$ .

Matter is defined as anything that ____________.

0%
occupies space and has mass
0%
has mass only
0%
occupies space only
0%
none of the above

Determine the number of electron in the isotope of 'H' (mass no. 2).

0%
1
0%
2
0%
0
0%
3

Matter is __________.

0%
everything around you
0%
anything that has mass and takes up space
0%
anything that has mass
0%
none of the above

Identify the incorrect statement.

0%
Charges on an electron and proton are equal and opposite.
0%
Neutron have no charge.
0%
Electron and proton have same mass.
0%
Masses of proton and neutron are nearly the same.

State whether the statement is true or false:

Isotopes are the atoms of the different element.

0%
True
0%
False

An atom contains eleven protons. State its atomic number and the number of electrons it contains.

0%
12, 12
0%
12, 11
0%
11, 11
0%
12, 13

An atom of an element has two electrons in the M shell. Identify its atomic number.

0%
10
0%
12
0%
14
0%
15

Explanation

For M shell value of

$n= 3$ . Thus the electronic configuration is : 2, 8, 2 and atomic number is 12.

According to whose atomic model, electrons are embedded in a gel of positive charge?

0%
Dalton's model
0%
Bohr's model
0%
Thomson's model
0%
Rutherford's model

Consider the following isotopes of chlorine:

$_{17}Cl^{35},_{17}Cl^{37}$ ,
Atomic masses of these isotopes are different, while their chemical properties are same. In the Mendeleev's periodic table isotopes of chlorine was placed:

0%
in the different groups
0%
in the same group
0%
in different periods
0%
both (A) and (C) are correct

If Aufbau rule is not followed in filling of sub orbitals, then block of the element will change in :

0%
K(19)
0%
Sc(21)
0%
V(23)
0%
Ni(28)

Explanation

If Aufbau rule is not followed,
electronic configuration is K:
1s

$^2$ 2s

$^2$ 2p

$^6$ 3s

$^2$ 3p

$^6$ 3d

$^1$ .
Last electron is in 3d(instead of

$4s$ ),
hence d block (but it is of

$s$ block)
in all other cases valence electron doesnt changes its position so block doesnt changes in those cases.

Which of the following properties can only be a whole number?

0%
Atomic mass
0%
Atomic volume
0%
Atomic radius
0%
Mass number

Bohr's atomic model can explain the spectrum of:

0%
hydrogen atoms only
0%
atoms or ions which are unielectron
0%
atoms or ions which have only two electrons
0%
hydrogen molecule

Many elements have non integral atomic masses because :

0%
they have isotopes
0%
their isotopes have non-integral masses
0%
their isotopes have different masses
0%
the constituents, neutrons, protons and electrons combine to give fractional masses

Explanation

Elements have non integral atomic masses because isotopes are having different masses and are occur in the nature in different proportion.

Eg.

$Cl\:; z= 17$ and

$A= 35$ and

$37$ . They are present in the ratio

$3:1$ .

$\therefore \cfrac {3\times35 + 1\times37}{4}=35.5$ (A)

Hence, options A & C are correct.

Atomic mass of an element is not necessarily a whole number becuase :

0%
it contains electrons, protons and neutrons
0%
it exists in all tropic forms
0%
it contains isotopes
0%
atoms are no longer indivisible

Matter can be defined as something that:

0%
Occupies space
0%
Has mass
0%
Exists in three states
0%
All of the above

Radioactivity is generally does not found in :

0%
light nuclei
0%
stable nuclei
0%
heavy nuclie
0%
nuclei of intermediate mass

Which statement about atom is incorrect?

0%
Atoms are invisible
0%
All atoms have same number of protons and electrons
0%
Atoms are made up of subatomic particles
0%
It has mass

Explanation

Atoms are smallest particle of an element.
They consists of solid mass in the center known as the nucleus in which protons and neutrons are present.
Outside the nucleus, there are present electrons which keep up on revolving around it.
Thus the atom is not mostly the empty space.
Hence this statement is $False$ .

State True or False.

Gamma rays produce maximum ionization in gases.

0%
True
0%
False

Explanation

Gamma rays produce minimum ionization in gases.
The ionizing power of

$\gamma-rays$ is very low.
The ionizing power of

$\alpha$ particles is about 100 times that of

$\beta$ particles.
The ionizing power of

$\beta$ particles is about 100 times that of

$\gamma$ rays.
The ionizing power of

$\alpha$ particles is very high.

Alpha particles are positively charged and contains the nucleus of ________ atom.

0%
$He$
0%
$H$
0%
$Li$
0%
$H^+$

Explanation

Alpha particles are positively charged. They are helium nuclei containing 2 protons and 2 neutrons. They carry 2 unit positive charge and 4 unit mass. They are represented as

$_2^4He$ .

Which of the following statements about radioactivity is/are true ?

0%
It involves outer electrons activity
0%
It is not affected by temperature or pressure
0%
It is an exothermic process
0%
The radioactivity of an element is not affected by any other element compounded by it

As a balloon is filled with water, it expands and increases in weight. This shows that water:

0%
Has mass
0%
Occupies space
0%
Is a kind of matter
0%
All of these

CBSE Questions for Class 11 Medical Chemistry Structure Of Atom Quiz 4 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

CBSE Questions for Class 11 Medical Chemistry Structure Of Atom Quiz 4 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

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