Structure of the Atoms Test

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Structure of the Atoms Test - 52

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Question 1
1 / -0

Positively charged radiation was discovered by?

A
Chadwick

B
Thomson

C
Goldstein

D
Bohr

Solution

Goldstein discovered the presence of positively charged radiations in a gas discharge in 1886 and called them canal rays. They are also known as anode rays. These rays later led to the discovery of positively charged particles called protons.
Question 2
1 / -0

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:

A
$$0.67x$$

B
$$1.67 x$$

C
$$2.67 x$$

D
$$2 x$$

Solution

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.
Question 3
1 / -0

Rutherford's alpha particle scattering experiment established that:

A
protons are not evenly distributed throughout an atom

B
electrons have a negative charge

C
electrons have a positive charge

D
atoms are made of protons, neutrons, and electrons

Solution

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.
Question 4
1 / -0

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

A
$$10^{-14}$$

B
$$10^{-12}$$

C
$$10^{-8}$$

D
$$10^{10}$$

Solution

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.
Question 5
1 / -0

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

A
nucleus

B
neutron

C
proton

D
electron

Solution

A majority of the mass of an atom is contributed by its protons and neutrons which reside inside the nucleus. Electrons have negligible mass, and so do not contribute much to the overall mass of the atom. So, the mass of the atom is concentrated in the nucleus.
Question 6
1 / -0

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?

A
All the alpha particles would have been deflected by the foil.

B
All the alpha particles should have bounced straight back from the foil.

C
Alpha particles should have passed through the foil with little or no deflection.

D
Alpha particles should have become embedded in the foil.

Solution

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.
Question 7
1 / -0

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?

A
Yes

B
No

C
Depends on the type of atom

D
Cannot be determined

Solution

Number of protons are equal to number of electrons in an atom. So, both the positive and negative charges are balanced and the atom is electrically neutral.
Question 8
1 / -0

The ratio of the energy of photon of $$2000 A^0$$ wavelength to that of $$4000 A^0$$ wavelength is:

A
1 : 4

B
4 : 1

C
1 : 2

D
2 : 1

Solution

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

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

Hence, option $$D$$ is correct.
Question 9
1 / -0

Which of the following doesn't have charge?

A
Proton

B
Neutron

C
Electron

D
Isotope

E
Ion

Solution

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.
Question 10
1 / -0

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.

A
true, false

B
false, true

C
false, false

D
true, true, correct explanation

Solution

$$^{12}C$$ 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.

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Re-Attempt Weekly Quiz Competition

Structure of the Atoms Test - 52

Result

Structure of the Atoms Test - 52

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SHARING IS CARING

Question 1

Chadwick

Thomson

Goldstein

Bohr

Solution

Question 2

$$0.67x$$

$$1.67 x$$

$$2.67 x$$

$$2 x$$

Solution

Question 3

protons are not evenly distributed throughout an atom

electrons have a negative charge

electrons have a positive charge

atoms are made of protons, neutrons, and electrons

Solution

Question 4

$$10^{-14}$$

$$10^{-12}$$

$$10^{-8}$$

$$10^{10}$$

Solution

Question 5

nucleus

neutron

proton

electron

Solution

Question 6

All the alpha particles would have been deflected by the foil.

All the alpha particles should have bounced straight back from the foil.

Alpha particles should have passed through the foil with little or no deflection.

Alpha particles should have become embedded in the foil.

Solution

Question 7

Yes

No

Depends on the type of atom

Cannot be determined

Solution

Question 8

1 : 4

4 : 1

1 : 2

2 : 1

Solution

Question 9

Proton

Neutron

Electron

Isotope

Ion

Solution

Question 10

true, false

false, true

false, false

true, true, correct explanation

Solution

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