Structure of Atom Test

Result

Structure of Atom Test - 78

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Weekly Quiz Competition

Question 1
1 / -0

In what region(s) of the spectrum does this series occur? Visible region is from $$360$$ to $$780\ nm$$.

A
Visible only

B
Infrarted only

C
Visible and infrared

D
Visible and ultraviolet

Solution
Question 2
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The time period of revolving in the third orbit of $$Li^{2+}$$ ion is $$x$$ second. The time period of revolution in the second orbit of $$He^+$$ ion should be

A
$$x\ s$$

B
$$\dfrac {3}{2}x\ s$$

C
$$\dfrac {2}{3}x\ s$$

D
$$\dfrac {8}{27}x\ s$$

Solution
Question 3
1 / -0

The energy of an electron in the first Bohr orbit for $$He^+$$ ion is $$-54.4eV.$$ Which one of the following is a possible excited state for electron in Bohr orbit of $$He^+$$ ion ?

A
$$-6.04eV$$

B
$$-6.08eV$$

C
$$-1.7eV$$

D
$$+1.36eV$$
Question 4
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Directions For Questions

A certain identical hydrogen-like alll its atoms in a particular upper energy level. The atoms make transition to a higher level when a monochromatic radiation, having wavelength $$4654\ \overset { o }{ A } $$, incident on it, Subsequent, the atoms emit radiation of only three different photon energies.

...view full instructions

The atom/ion is

A
$$H$$

B
$$D$$

C
$$He^{+}$$

D
$$Li^{+2}$$

Solution
Question 5
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In the Bohr's model of the hydrogen atom, let r, v and E represent the orbit radius, speed of the electron, respectively. Which of the following relation is proportional to the orbit number $$n$$?

A
$$v\cdot r$$

B
$$r/E$$

C
$$r/V$$

D
$$r\cdot E$$

Solution
Question 6
1 / -0

The energy emitted when electron of $$1.0\ g$$ atom of hydrogen undergo transition giving the spectral lines of lowest energy in visible region of its atomic spectra is

A
$$301.22\ kJ$$

B
$$328\ kJ$$

C
$$984\ kJ$$

D
$$182.22\ kJ$$

Solution

The transition occurs like Balmer series as spectral line is observed in visible region.

Thus, the line of lowest energy will be observed when transition occurs from 3rd orbit to 2nd orbit

that is $$ n_{f} = 2 $$ and $$ n_{i} = 3 $$

from the formula

$$\frac{1}{\lambda} = R(\frac{1}{n_{f} ^{2}}- \frac{1}{n_{i}^{2}}) $$

putting values and we get;

$$ \frac{1}{\lambda} = \frac{5R}{36} $$

As we know ;

E = hf

$$ E= h\frac{c}{\lambda} $$

$$ c = 3 \times 10^{8} $$

$$ \frac{1}{\lambda} = \frac{5R}{36} $$

putting the value of c and $$ \lambda $$ in above energy equation ; we get
E = $$ 3.03 \times 10^{-19} $$ j per atom

Energy corresponding to 1.0g atom of hydrogen

E = $$ 3.03 \times 10^{-19} \times avagadro -no. $$ (in kJ)

$$\therefore $$ E = 182.22KJ
Question 7
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The spectrum of helium is similar to:

A
$$H$$

B
$$Na$$

C
$$Li^+$$

D
$$He^+$$

Solution
Question 8
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Directions For Questions

In the manufacture of iron, a gas (A) is formed in the zone of combustion of the blast furnace. The gas (A) reacted with coke in the zone of fusion to form another gas (B). X moles of (B) reacts with iron at $$200^o$$C and $$100$$ atm pressure to form a compound (C).

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The d orbital(s) involved in the formation of the complex(C) will be?

A
$$d_{z^2}$$

B
$$d_{x^2-y^2}$$ and $$d_{z^2}$$

C
$$dxy$$ and $$d_{x^2-y^2}$$

D
$$d_{x^2-y^2}$$

Solution
Question 9
1 / -0

All of the following possess complete d-shells except:

A
$$Ag^+$$

B
$$Cu^{2+}$$

C
$$Ga^{3+}$$

D
$$Zn^{2+}$$

Solution
Question 10
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Bohr model of an atom could not account for :

A
Emission spectrum

B
Absorption spectrum

C
Line spectrum of hydrogen

D
Fine spectrum

Solution

Bohr's model breaks down when applied to multi-electron atoms. It does not account for sublevel $$(s\ ,\ p\ ,\ d\ ,\ f)$$ orbitals or electron spin. Bohr's model allows only the classical behavior of an electron (orbiting the nucleus at discrete distances from the nucleus). Thus, the concept of orbitals is thrown out.

Bohr's model failed in explaining the line spectrum of multi-electron species. Hence, Bohr's model could not explain the emission spectrum.

Hence, option (A) is correct.