Structure of Atom Test

Result

Structure of Atom Test - 8

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Weekly Quiz Competition

Question 1
4 / -1

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

A
Heisenberg

B
Bohr

C
Planck

D
Einstein

Solution

Bohr's theory was based upon some postulations of classical physics and some postulations of the newly proposed quantum theory of Planck.
Question 2
4 / -1

The wavelength associated with a golf ball weighing 200g and moving at a speed of 5m/h is of the order:

A
10^-10 m

B
10^-20 m

C
10^-30m

D
10^-40 m

Solution

From de Broglie wavelength formula; λ = h/p where h=Planck's constant and p=momentum.
Putting all the values, we have h=6.626×10^-34/(200/1000)(5/3600)
= 2.3853×10^-30
Order is of 10^-30
Question 3
4 / -1

The longest wavelength of He⁺ in Paschen series is "m", then shortest wavelength of Be³⁺ in Paschen series is (in terms of m) :

A

B

C

D

Solution

The expression for the wavelength is :

For the longest wavelength of the He+ atom in Paschen series , the expression becomes
(1)
For the shortest wavelength of the expression becomes
(2)
Divide equation (2) with equation (1).
On solving this, we get λ=7/64m
Question 4
4 / -1

What is uncertainity in location of a photon of wavelength 5000 Å if wavelength is known to an accuracy of 1 pm?

A
7.96 × 10^-14 m

B
0.02 m

C
3.9 × 10^-8m

D
none

Solution

0.0199 m
Question 5
4 / -1

Consider the following nuclear reactions involving X & Y.

If both neutrons as well as protons in both the sides are conserved in nuclear reaction then moles of neutrons in 4.6 gm of X :

A
2.4 N_A

B
2.4

C
4.6

D
0.2 N_A

Solution

By conservation of mass
X = 4 + 18 + 1 gm
= 23
23 gm → (2 + 10) moles neutrons.
Question 6
4 / -1

Electromagnetic radiations having λ = 310 Å are subjected to a metal sheet having work function = 12.8 eV. What will be the velocity of photoelectrons with maximum Kinetic energy.

A
0, no emission will occur

B
2.18 × 10⁶ m/s

C
10⁶ m/s

D
8.72 × 10⁶ m/s

Solution

V² = 9.56 × 10¹²
V = 3.09 × 10⁶ m/sec.
Question 7
4 / -1

Assuming Heisenberg Uncertainity Principle to be true what could be the miniumum uncertainity in de–Broglie wavelength of a moving electron accelerated by Potential Difference of 6V whose uncertainity in position is 7/22 n.m.

A
6.25 Å

B
6 Å

C
0.625 Å

D
0.3125 Å

Solution
Question 8
4 / -1

A 1-kW radio transmitter operates at a frequency of 880 Hz. How many photons per second does it emit -

A
1.71 x 10²¹

B
1.71 x 10³³

C
6.02 x 10²³

D
2.85 x 10²⁶

Solution

Given :
P = 1 kW
P = 1 × 10³ watt
E = 10³ J/S in one sec
v = 880 Hz
∴ E = nhv
⇒ 10³ x × 6.626 × 10^–34 × 880
⇒ x = 1.71 × 10³³ in one sec
Question 9
4 / -1

The value of Bohr radius of hydrogen atom is -

A
0.529x 10^–7cm

B
0.529x 10^–8cm

C
0.529x 10^–9cm

D
0.529x 10^–10 cm

Solution

= 0.529 × 10^–10 m
= 0.529 × 10^–8 cm
Question 10
4 / -1

On the basis of Bohr's model, the radius of the 3rd orbit is -

A
Equal to the radius of first orbit

B
Three times the radius of first orbit

C
Five times the radius of first orbit

D
Nine time the radius of first orbit

Solution