Which of the following observations from Rutherfords experiment disprove Thomsons proposal that the atom is a positively charged sphere? Observation I Most of the fast-moving $$\alpha$$- particles passed straight through the gold foil. Observation II Some of the $$\alpha$$- particles were deflected by the foil by small angles. Observation III One out of every $$12000$$ particles appeared to rebound.

None of these observations disprove Thomsons model

MCQ Questions for Class 9 Chemistry Structure Of The Atom Quiz 14

If the atomic number of an atom is

$17$ and the mass number is

$35$ then the number of neutrons will be

0%
$35$
0%
$17$
0%
$18$
0%
$52$

Explanation

The formula to calculate mass number is,

Mass number = number of protons + number of neutrons

Number of neutrons = mass number - number of protons =

$35-17$ =

$18$ .

Option

$C$ is correct.

Rutherford's

$\alpha-$ particle scattering experiment discovered

0%
Electron
0%
Proton
0%
Atomic nucleus
0%
Neutron

Explanation

Nucleus of the atom that is positively charged was discovered by Rutherford's

$\alpha-$ particle scattering experiment.

Which type of radiations were used in Rutherford's experiment ?

0%
$\alpha$
0%
$\beta$
0%
$\gamma$
0%
$\lambda$

Explanation

In Rutherford's experiment,

$\alpha$ particle was bombarded on thin gold foil and observed that nucleus occupy a very small portion of the atom.
So option

$A$ is correct.

$\alpha$ -particle scattering experiment, one out of every 12000 particles appeared to rebound. This unexpected result was discovered by which scientist?

0%
Willard
0%
Roentgen
0%
Chadwick
0%
Rutherford

Explanation

Rutherford made this observation in his

$\alpha-$ particle scattering experiment. Based on this observation, he concluded that all the positive charge and mass of the atom is concentrated in a very small volume within the atom.

According to Rutherford's suggestion how many times smaller should be the atomic nucleus than the total area of an atom?

0%
$10^{15}$
0%
$10^{10}$
0%
$10^{8}$
0%
$10^{5}$

Explanation

While performing experiments on gold foil and alpha radiations, Rutherdford found from his calculations that atomic nucleous is

$10^{5}$ times smaller than the total area of the atom.

Which sub-atomic particles revolve around the nucleus?

0%
Protons
0%
Neutrons
0%
Electrons
0%
None of these

The discovery of nucleus was done by

0%
J. J. Thomson
0%
Chadwick
0%
Rutherford
0%
Moseley

State True or False:
No current flows through the discharge tube when the pressure of the gas inside is one atmosphere.

0%
True
0%
False

Which of the following observations from Rutherfords experiment disprove Thomsons proposal that the atom is a positively charged sphere?

Observation I	Most of the fast-moving $\alpha$ - particles passed straight through the gold foil.
Observation II	Some of the $\alpha$ - particles were deflected by the foil by small angles.
Observation III	One out of every $12000$ particles appeared to rebound.

0%
Observation I only
0%
Observation III only
0%
Observations II and III
0%
None of these observations disprove Thomsons model

Explanation

Very few of bombarded

$\alpha$ -particles on gold foil were deflected by sharp angles and therefore, it was concluded that the positive charge is concentrated in a very small volume of the atom called nucleus. Since few were deflected, the size of the nucleus is very small as compared with atom size. Most of particles passed through the foil un deflected and was concluded that most of space in an atom is empty.

So correct option is B.

State True or False:

The mass of a proton and a neutron is taken as one unit each.

0%
True
0%
False

Which of the following atom has no neutron in its nucleus ?

0%
Helium
0%
Lithium
0%
Protium
0%
Tritium

Explanation

Protium is the most abundant isotope of hydrogen with an abundance of almost 99%. It's symbol is

$H^{1}_{1}$ . Its atomic number is 1 and its mass number is also 1. So it does not possess any neutron.
Whereas,
Helium,

$He^{4}_{2}$ , has 2 neutrons

Lithium,

$Li^{7}_{3}$ , has 4 neutrons
Tritium,

$H^{3}_{1}$ , has 2 neutrons

The correct option is

$C$ .

Positively charged radiation was discovered by?

0%
Chadwick
0%
Thomson
0%
Goldstein
0%
Bohr

An atom as a whole is electrically neutral because the number of protons is equal to the number of electrons. Is the given statement true?

0%
Yes
0%
No
0%
Depends on the type of atom
0%
Cannot be determined

The atomic mass of an atom is the sum of the atom's neutrons and protons.

0%
True
0%
False

In Rutherford's experiment, a thin gold foil was bombarded with alpha particles. If 'Thomson's Plum-Pudding' model of the atom was applicable, then what should have happened?

0%
All the alpha particles would have been deflected by the foil.
0%
All the alpha particles should have bounced straight back from the foil.
0%
Alpha particles should have passed through the foil with little or no deflection.
0%
Alpha particles should have become embedded in the foil.

Explanation

According to 'Thomson's Plum-Pudding' model, a positive charge is spread over a sphere in which the electrons are embedded to make the atom as a whole neutral. If

$\alpha$ -particles were bombarded over this charge-neutral sphere,

$\alpha$ -particles should have passed through the foil with a little deflection or straight because

$\alpha$ particles are positively charged (

$He^{2+}$ ) particles and they would have experienced no net force on them as the charge would have been uniformly spread, but that wasn't the case and the alpha particles were deflected, disapproving Thomas' model of the atom.

In Bohr's model of an atom :

0%
Electrons revolve around the nucleus in circular orbits.
0%
These circular orbits or shells are stationary.
0%
Each shell in associated with a definite amount of energy.
0%
All shells have equal energy level.

Which of the following statements is NOT true?

0%
The particles which are present in an atom are known as sub-atomic particles
0%
The particles which are present in a nucleus are known as nucleons.
0%
An alpha particle is a doubly ionized helium nucleus.
0%
The mass of an electron is $1.06\times 10^{-19}g$

Explanation

An electron has mass. It weighs

$9.1 \times 10^{-31}$ kilograms.

In a particular set-up, the Rutherford alpha ray scattering experiment using thin gold foil,

$\displaystyle N(\theta )$ is found to be

$x$ . If a platinum foil of double thickness is used instead,

$\displaystyle N(\theta )$ would be:

0%
$0.67x$
0%
$1.67 x$
0%
$2.67 x$
0%
$2 x$

Explanation

The scattering process can be treated statically in terms of the cross-section for interaction with the nucleus which is considered to be a point charge

$Ze$ for a detector at a specific angle with respect to being incident beam. The number of particles per unit area striking the detector,

$\displaystyle N(\theta )=\frac{N_{1}nLZ^{2}K^{2}e^{4}}{4r^{2}(KE)^{2}\sin ^{4}(\theta /2)}$ .

$\displaystyle N_{1}$ = Number of incident alpha particles

$n =$ Atoms per unit volume in garget

$L =$ Thickness of target

$Z =$ Atomic number of target

$K =$ Coulomb's constant

$e =$ Electronic charge

$r =$ Target to detector distance

$KE =$ Kinetic energy of alpha particles

$\displaystyle \theta =$ Scattening angle
so according to equacation

$\displaystyle \theta$ is directly proposnal to thinkness of target so when we double the thickness of target then

$\displaystyle \theta$ also will be doubled.
hence answer is option D.

Rutherford's alpha particle scattering experiment established that:

0%
protons are not evenly distributed throughout an atom
0%
electrons have a negative charge
0%
electrons have a positive charge
0%
atoms are made of protons, neutrons, and electrons

Explanation

Most of the

$\alpha$ -particle passed through the foil straight without suffering any change in their direction. This shows that most of the space inside the atom is empty or hollow.

A small fraction of

$\alpha$ -particles was deflected through small angles and a few through larger angles. For this to happen

$\alpha$ - particles (positively charged) must approach a heavy positively charged core inside the atom (like charges repel each other). This heavy positively charged core inside the atom was named the nucleus.

Hence, it concluded that protons are not distributed throughout an atom.

Therefore, option A is correct.

The density of nucleus is about _______ times the density of atom.

0%
$10^{-14}$
0%
$10^{-12}$
0%
$10^{-8}$
0%
$10^{10}$

Explanation

The density of the nucleus is about

$10^{10}$ times the density of atom.
This is because the maximum mass of atom is concentrated in nucleus and volume of nucleus is less. So density of the nucleus will be always greater than of atom.

The mass of an atom is concentrated inside the ............. of an atom.

0%
nucleus
0%
neutron
0%
proton
0%
electron

The ratio of the energy of photon of

$2000 A^0$ wavelength to that of

$4000 A^0$ wavelength is:

0%
1 : 4
0%
4 : 1
0%
1 : 2
0%
2 : 1

Explanation

$E=\cfrac { hc }{ \lambda } \Rightarrow E\propto \cfrac { 1 }{ \lambda }$

$\therefore \cfrac { { E }_{ 1 } }{ { E }_{ 2 } } =\cfrac { { \lambda }_{ 2 } }{ { \lambda }_{ 1 } } =\cfrac { 4000 }{ 2000 } =2:1$

Hence, option

$D$ is correct.

Which of the following doesn't have charge?

0%
Proton
0%
Neutron
0%
Electron
0%
Isotope
0%
Ion

Explanation

Neutron has zero unit charge.
The neutron is a subatomic particle, symbol

$n$ or

$n^0$ , with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons, each with mass approximately one atomic mass unit, constitute the nucleus of an atom, and they are collectively referred to as nucleons.

Statement I :

$\displaystyle ^{ 12 }{ C }\$ is an isotope of

$\displaystyle ^{ 14 }{ C }\$ .
Statement II: The nuclei of both atoms have the same number of neutrons.

0%
true, false
0%
false, true
0%
false, false
0%
true, true, correct explanation

Explanation

$^{12}C$ is an isotope of

$^{14}C$ .

As isotopes are variants of a particular chemical element that differ in neutron number but have the same number of protons.

$^{12}C$ has

$12 - 6 = 6$ neutrons.

$^{14}$ has

$14 - 6 = 8$ neutrons.

Hence, the statement

$I$ is true but the statement

$II$ is false.

According to Rutherford's model of an atom:

0%

There is a positively charged centre in an atom called the nucleus.
0%
Electrons never lose or gain energy.
0%

The electrons revolve around the nucleus in circular paths.
0%
Electrons do not move at all.

If Rutherford would have used

$\beta$ -particles instead of

$\alpha$ -particles in his Goldleaf experiment which of the following observation would definitely not have been made?

0%
Get condensed or concentrated
0%
Majority of $\beta$ -particles passing unperfected through the foil
0%
Very few $\alpha$ -particles getting absorbed
0%
Wave nature of electron

If one were to apply Bohr's model to a particle of mass 'm' and charge 'q' moving in a plane under the influence of a magnetic field 'B', the energy of the charged particles in the

$n^{th}$ level will be:

0%
n $(\dfrac{hqB}{8\pi m})$
0%
n $(\dfrac{hqB}{4\pi m})$
0%
n $(\dfrac{hqB}{2\pi m})$
0%
n $(\dfrac{hqB}{\pi m})$

Explanation

According to given data

We know that,

$mvr=\dfrac{nh}{2\pi }$

Or,

$qvB=\dfrac{m{{v}^{2}}}{r}$

So we find,

$qB=\dfrac{mv}{r}$

$qB\left( \dfrac{nh}{2\pi mv} \right)=mv$

$\left( \dfrac{1}{2}m{{v}^{2}} \right)=\dfrac{nhqB}{4\pi m}$

$E=n\left( \dfrac{hqB}{4\pi m} \right)$

This is the required solution.

One Bohr magneton is equal to ____________

${ AM }^{ 2 }$ .

0%
$4.8\times { 10 }^{ -10 }eSu$
0%
$1.6\times { 10 }^{ -19 }eSu$
0%
$4.8\times { 10 }^{ -10 }\ eSu\ \& 1.6\times { 1 0}^{ -19 } \ eSu$
0%
$9.27\times { 10 }^{ -24 }$

Which of the following concept was considered in Rutherford's atomic model?

0%
The electrical neutrality of atom
0%
Electrons revolve around nucleus at a very high speed
0%
Existence of nuclear forces of attraction on the electrons.
0%
All of the above

Which of the following are isotopes?
(i) Atom, whose nucleus contains 20p+15n
(ii) Atom whose nucleus contains 20p+17n
(iii) Atom, whose nucleus contains 18p+22n
(iv) Atom, whose nucleus contains 18p+21n

0%
(i) and (iii)
0%
(i) and (ii)
0%
(ii) and (iii)
0%
(ii) and (iv)

CBSE Questions for Class 9 Chemistry Structure Of The Atom Quiz 14 - MCQExams.com

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CBSE Questions for Class 9 Chemistry Structure Of The Atom Quiz 14 - MCQExams.com

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Practice Class 9 Chemistry Quiz Questions and Answers

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