Structure of Atom Test

Result

Structure of Atom Test - 73

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Weekly Quiz Competition

Question 1
1 / -0

In an atom the order of increasing energy of electrons with quantum numbers.
i) $$n=4,l=1$$ ii) $$n=3,l=2$$ iii) $$n=3,l=1$$ iv) $$n=4,l=0$$

A
$$iii < i < iv < ii$$

B
$$iii < iv < ii < i$$

C
$$iv < ii < iii < i$$

D
$$iii < iv < i < ii$$
Question 2
1 / -0

Which principle/ rule limits the maximum number of electrons in orbital to two?

A
Aufbau principle

B
Pauli's exclusion principle

C
Hund's rule of maximum multiplicity

D
Heisenberg's uncertainty principle

Solution
Question 3
1 / -0

Find an expression for de Broglie wavelength for an electron in the $$n^{th}$$ orbit of the Bohr model of the hydrogen atom and hence find its value when the electron is in n = 4 level.
Take radius of nth orbital of Bohr's model of H-atom; $$r_n = (53 \ n^2) $$ pm

A
1.33 nm

B
1.20 nm

C
1.50 nm

D
None

Solution
Question 4
1 / -0

An electron jumps from the $$4^{th}$$ orbit to the $$2^{nd}$$ orbit of hydrogen atom $$(R=10^{5}\ Cm^{-1})$$. Frequency is in $$Hz$$ of emitted radiation will be

A
$$\dfrac {3\ \times 10^{5}}{16}$$

B
$$\dfrac {3\ \times 10^{15}}{16}$$

C
$$\dfrac {9\ \times 10^{15}}{16}$$

D
$$\dfrac {9\ \times 10^{5}}{16}$$

Solution

$$\begin{array}{l}\text { Electron jumps from } 4^{\text {th }} \text { orbit to } \\2^{\text {nd }} \text { orbit. } \\\text { Let wavelength be "x" then } \\\qquad \frac{1}{\lambda}=R Z^{2}\left[\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right]\end{array}$$

$$\text { Here, } \begin{aligned}& R=10^{5} \mathrm{~cm}^{-1} \\& z=1\\& n_{1}=2, n_{2}=4 \\\frac{1}{\lambda} &=10^{5}\left[\frac{1}{2^{2}}\frac{1}{4^{2}}\right] \\\frac{1}{\lambda}&=10^{5}\left[\frac{1}{4}-\frac{1}{16}\right] \\\frac{1}{\lambda} &=10^{5}\left[\frac{3}{16}\right] \\\frac{1}{\lambda} &=\frac{3 \times 10^{5}}{16}-(1)\end{aligned}$$

$$\begin{array}{l}\text { Frequency is } \frac{c}{\lambda} \\c=3 \times 10^{8} \mathrm{~m}=3 \times 10^{10} \mathrm{~cm} \\\text { From frequency, } v=3 \times 10^{10} \times \dfrac{3 \times 10^{5}}{16}\\\qquad v=\dfrac{9 \times 10^{15}}{16}\end{array}$$
Question 5
1 / -0

For a nucleus to be stable, the correct relation between neutron number N and proton number Z is

A
N>Z

B
N=z

C
N<Z

D
$$N \geqslant Z$$

Solution
Question 6
1 / -0

Which of the following radiations has largest energy ?

A
$$\lambda = 30$$ nm

B
$$\lambda = 300$$ pm

C
$$v = 3\times 10^{12}$$ s$$^{-1}$$

D
$$v = 3\times 10^{10}$$ s$$^{-1}$$

Solution
Question 7
1 / -0

According to Bohr's theory of the hydrogen atom, the speed $$v_n$$ of the electron in a stationary orbit is related to the principal quantum number n as (C is a constant).

A
$$v_n=C/n^2$$

B
$$v_n=C/n$$

C
$$v_n=C\times n$$

D
$$v_n=C\times n^2$$

Solution
Question 8
1 / -0

Atomic number of $$N$$ is $$7$$. The atomic number of 3rd member of nitrogen family is

A
23

B
15

C
33

D
43

Solution

Period I II III IV V
Element N P $$As$$ Sb Bi
Atomic no. 7 15 $$33$$ 51 83
The atomic number of 3rd member of nitrogen family is $$33.$$
Question 9
1 / -0

In a hypothetical system a particle of mass m and charge -3 q is moving around a very heavy particle having charge q. Assuming Bohr's model to be true to this system, the orbital velocity of mass m when it is nearest to heavy particle is:

A
$$\frac{3q^2}{2\varepsilon _0h}$$

B
$$\frac{3q^2}{4\varepsilon _0h}$$

C
$$\frac{3q}{2\varepsilon _0h}$$

D
$$\frac{3q}{4\varepsilon _0h}$$

Solution
Question 10
1 / -0

Three photons originating from exited atomic hydrogen atoms are found to have energies of 0.66 eV, 1.89 eV and 2.55 eV respectively. The minimum no. of atoms that must be present are :

A
one atom

B
two atoms

C
three atoms

D
cant say.

Solution