Structure of Atom Test

Result

Structure of Atom Test - 79

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Weekly Quiz Competition

Question 1
1 / -0

The French physicist Louis de Broglie in 1924 postulated that matter, like radiation, should exhibit a dual behaviour. He proposed the following relationship between the wavelength $$\lambda$$ of a material particle, its linear momentum p and Planck constant h. $$\lambda=\dfrac {h}{p}=\dfrac{h}{mv}$$. The de Broglie relation implies that the wavelength of a particle should decrease as its velocity increases. It also implies that for a given velocity heavier particles should have a shorter wavelength than lighter particles. The waves associated with particles in motion are called matter waves or de Broglie waves. These waves differ from the electromagnetic waves as they (i) have lower velocities (ii) have no electrical and magnetic fields and (iii) are not emitted by the particle under consideration. The experimental confirmation of the de Broglie relation was obtained when Davisson and Germer, in 1927, observed that a beam of electrons is diffracted by a nickel crystal. As diffraction is a characteristic property of waves, hence the beam of electron behaves as a wave as proposed by de Broglie.

Using Bohr's theory, the transition, so that the electrons de-Broglie wavelength becomes 3 times of its original value in $$He^{+}$$ ion will be

A
$$2 \rightarrow 6$$

B
$$2 \rightarrow 4$$

C
$$1 \rightarrow 4$$

D
$$1 \rightarrow 6$$

Solution
Question 2
1 / -0

Aluminium chloride exists as a dimer because aluminium has______

A
greater $$I.P.$$

B
incomplete $$p-$$orbital

C
larger radius

D
high nuclear charge

Solution
Question 3
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Electron enters the sub-shell for which $$(n+l)$$ value is minimum. This is enunciated as

A
Hunds rule

B
Aufbau principle

C
Heisenberg uncertainty principle

D
Paulis exclusion principle

Solution
Question 4
1 / -0

The phenomenon of radioactivity arises from the

A
Binary fission

B
Nuclear fusion

C
Stable nuclei

D
Decay of unstable nuclei

Solution
Question 5
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The energy of a 2p orbital except hydrogen atom is

A
Less than that of 2s orbital

B
More than that of 2s orbital

C
Equal to that of 2s orbital

D
Double that of 2s orbital

Solution
Question 6
1 / -0

The electrons would go to lower energy levels first and then to higher energy levels according to which of the following

A
Aufbau principle

B
Pauli's exclusion principle

C
Hund's rule of maximum multiplicity

D
Heisenberg's uncertainty principle

Solution
Question 7
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Which of the following sequence is correct as per Aufbau principle?

A
$$3s < 3d < 4s < 4p$$

B
$$1s < 2p < 4s < 3d$$

C
$$2s < 5s < 4p < 5d$$

D
$$2s < 2p < 3d < 3p$$

Solution
Question 8
1 / -0

Artificial elements have been prepared by bombardment reactions in high energy accelerators. What is the mass number of the element X produced in the following nuclear reaction?

$$_{95}^{249} Cf + _7^{15} N \rightarrow _{105}X + 4 _0^1 n$$

A
261

B
264

C
260

D
257

Solution

Equating the mass number on both sides of reaction , we get:

               $$249 + 15 = x + 4$$
               $$x= 260$$

Hence mass number of element $$X$$ is $$260$$
Option (C) is correct.
Question 9
1 / -0

According to Aufbau's principle, which of the three $$4d, 5p$$ and $$5s$$ will be filled with electrons first

A
$$4d$$

B
$$5p$$

C
$$5s$$

D
$$4d$$ and $$5s$$ will be filled simultaneously

Solution
Question 10
1 / -0

The figure shows a graph between $$\ln \left|\dfrac {A_n}{A_1}\right|$$ and $$1n |n|$$ where $$A_n$$ is the area enclosed by the $$n^{th}$$ orbit in a hydrogen like atom. The correct curve is

A
$$4$$

B
$$3$$

C
$$2$$

D
$$1$$

Solution

$$A_n=\pi r_n^2 \Rightarrow \dfrac {A_n}{A_1} =\left(\dfrac {r_n}{r_1}\right)^2 =\left (\dfrac {n}{1}\right)^4 \quad (\because r_n \propto n^2)$$
Taking $$\log_e $$ both side $$\log_e \dfrac {A_n}{A_1}=4\log_e(n)$$
Comparing it with $$y=mx+c$$, graph $$(4)$$ is correct.