Q: In the lowest energy level of hydrogen atom, electron has an angular momentum equal to:

The angular momentum\$ L\$ \$=m_{e}vr\$ is on integer multiple of \$\dfrac{h}{2\pi }\$\$mvr=\dfrac{nh}{2\pi}\$ For, \$n=1\$\$mvr=\dfrac{h}{2\pi}\$

Q: The total number of neutrons in all isotopes of hydrogen is equal to:

Hydrogen has 3 isotopes. \$_{1}^{1}\textrm{H} \$ \$_{1}^{2}\textrm{H}\$ \$_{1}^{3}\textrm{H}\$neutron 0 1 2proton 1 1 1 The total number of neutrons in all the isotopes of Hydrogen \$=0+1+2=3\$.

Q: A sample of rock from moon contains equal number of atoms of uranium and lead \$(\mathrm{t}_{\frac{1}{2}}\$ for \$\mathrm{U}=4.5\times 10^{9}\$ years \$)\$. The age of the rock would be

\$ t_{1/2}=\frac{0.693}{k} \$\$ \therefore k=\frac{0.693}{45x10^{g}}years^{-1} \$It is an uranium dating technique,\$ \therefore Age=\frac{2.303}{K}log_{10}[1+\frac{Pb^{206}}{U^{238}}] \$ \$ =\frac{2.303}{0.693}x45x10^{g}log_{10}[1+1] \$ \$ =\frac{2.303x45x10^{g}}{0.693}log_{10}(2) \$ Age = 4 x 10\$ ^{g} \$ years

Question 1

In the lowest energy level of hydrogen atom, electron has an angular momentum equal to:

Accepted Answer

The angular momentum$ L$ $=m_{e}vr$ is on integer multiple of $\dfrac{h}{2\pi }$$mvr=\dfrac{nh}{2\pi}$ For, $n=1$$mvr=\dfrac{h}{2\pi}$

Question 2

The total number of neutrons in all isotopes of hydrogen is equal to:

Accepted Answer

Hydrogen has 3 isotopes.               $_{1}^{1}\textrm{H}  $      $_{1}^{2}\textrm{H}$          $_{1}^{3}\textrm{H}$neutron  0        1         2proton     1       1            1 The total number of neutrons in all the isotopes of Hydrogen $=0+1+2=3$.

Question 3

Which of the following is/are true as per Thomson's model of atom?

Accepted Answer

Thomson's model of atom states that:1. An atom consists of a positively&#10;charged sphere with electrons embedded in it.2. Total positive and negative charges in the atom are equal in magnitude. So, atom is electrically neutral.

Question 4

A sample of rock from moon contains equal number of atoms of uranium and lead $(\mathrm{t}_{\frac{1}{2}}$ for $\mathrm{U}=4.5\times 10^{9}$ years $)$. The age of the rock would be

Accepted Answer

$ t_{1/2}=\frac{0.693}{k} $$ \therefore k=\frac{0.693}{45x10^{g}}years^{-1} $It is an uranium dating technique,$ \therefore Age=\frac{2.303}{K}log_{10}[1+\frac{Pb^{206}}{U^{238}}] $            $ =\frac{2.303}{0.693}x45x10^{g}log_{10}[1+1] $            $ =\frac{2.303x45x10^{g}}{0.693}log_{10}(2) $          Age = 4 x 10$ ^{g} $ years

Question 5

The main defect of Bohr's atom model is :

Accepted Answer

Bohr's model can only clearly explain hydrogen or hydrogen-like atoms, it fails when applied to larger and heavier atoms like iron, gold, mercury, etc.

Question 6

The $d_{z^{2}}$ orbital can give room only to:

Accepted Answer

Any orbital can give room only to 2 electrons (maximum)

Question 7

Which of the following properties are similar for isotopes?

Accepted Answer

Toppr Ask Answer

Question 8

To which of the following is Bohr's theory applicable:I) $He^{+}$ II) $Li^{2+}$III) Tritium  IV) $Be^{2+}$The correct combination is:

Accepted Answer

Bohr's atomic model explains the spectra of single-electron atoms like $H$-atom. It does not explain the spectra of multi-electron atoms. So the atoms which are isoelectronic and have the same electronic configuration are well explained by this atomic model.$He^+$, $Li^{2+}$ and tritium $_{ 1 }{ H }^{ 3 }$ have same number of electrons as that of hydrogen atom i.e. $1$ while $Be^{2+}$ is formed by losing $2e$. So, it is a two-electron system.Option D is correct.

Question 9

The atomic number at which filling of a g-orbital is likely to begin is:

Accepted Answer

The above question can be answered on the basis of reasoning from analogy. We note that two periods have to pass before d-orbitals begin to fill. This is also true of the spot where f-orbitals commence filling. The second row where f-orbitals fill happens to be row #7 (the one starting with Fr). The first element where 5f-orbitals enter in is actinium (Ac, Z = 89). Adding 32 to this would give element #121 termed as Unbiunium, the first Super-Actinide.

Question 10

The band spectrum is caused by:

Accepted Answer

Hint: Band spectrum arises because of electron transition between the valence band and conduction band.Explanation:The band spectrum is caused by molecules. The energy levels of molecules are so close to each other that they combine to form a band. The valence band and conduction band are two types of bands. Electron transition between these two bands forms band spectrum.For example a spectrum of air. The bright bands are due to molecular oxygen (O$_2$), molecular nitrogen (N$_2$), and other molecules.So from the above example, it is clear that Option A is the answer.

Structure Of Atom

Chemistry
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In the lowest energy level of hydrogen atom, electron has an angular momentum equal to:

The total number of neutrons in all isotopes of hydrogen is equal to:

Which of the following is/are true as per Thomson's model of atom?

A sample of rock from moon contains equal number of atoms of uranium and lead $(t_{\frac{1}{2}}$ for $U = 4.5 \times 1 0^{9}$ years $)$ . The age of the rock would be

The main defect of Bohr's atom model is :

The $d_{z^{2}}$ orbital can give room only to:

Which of the following properties are similar for isotopes?

To which of the following is Bohr's theory applicable:
I) $H e^{+}$
II) $L i^{2 +}$
III) Tritium
IV) $B e^{2 +}$
The correct combination is:

The atomic number at which filling of a g-orbital is likely to begin is:

The band spectrum is caused by:

Structure Of Atom

Chemistry 2112 Views

In the lowest energy level of hydrogen atom, electron has an angular momentum equal to:

The total number of neutrons in all isotopes of hydrogen is equal to:

Which of the following is/are true as per Thomson's model of atom?

A sample of rock from moon contains equal number of atoms of uranium and lead (t21​​ for U=4.5×109 years ). The age of the rock would be

The main defect of Bohr's atom model is :

The dz2​ orbital can give room only to:

Which of the following properties are similar for isotopes?

To which of the following is Bohr's theory applicable: I) He+ II) Li2+ III) Tritium IV) Be2+ The correct combination is:

The atomic number at which filling of a g-orbital is likely to begin is:

The band spectrum is caused by:

Chemistry
2112 Views

A sample of rock from moon contains equal number of atoms of uranium and lead $(t_{\frac{1}{2}}$ for $U = 4.5 \times 1 0^{9}$ years $)$ . The age of the rock would be

The $d_{z^{2}}$ orbital can give room only to:

To which of the following is Bohr's theory applicable:
I) $H e^{+}$
II) $L i^{2 +}$
III) Tritium
IV) $B e^{2 +}$
The correct combination is: