### Physics - Atoms , Molecules And Nuclei

#### Question - 1

In Rutherford's experiment, silver foil is replaced by a copper foil of the same thickness. The number of alpha particles scattered through the same angle per minute in copper foil is proportional to

• A $\frac { { Z }_{ Cu } }{ { Z }_{ Ag } }$
• B ${ \left( \frac { { Z }_{ Cu } }{ { Z }_{ Ag } } \right) }^{ 2 }$
• C $\frac { { Z }_{ Ag } }{ { Z }_{ Cu } }$
• D ${ \left( \frac { { Z }_{ Ag } }{ { Z }_{ Cu } } \right) }^{ 2 }$

#### Question - 2

Alpha particles that come closer to nuclei

• A are deflected more
• B are deflected less
• C are slowed down more
• D make more collisions with nuclei

#### Question - 3

In Rutherford's experiment on alpha particle scattering, the ratio of number of alpha particles through an angle of 60° and 90° is

• A 4 : 1
• B $\sqrt { 3 } :1$
• C 3 : 1
• D 9 : 1

#### Question - 4

Rutherford's atomic model has the deficiencies, namely,

• A since electron has centripetal acceleration, it must fall into nucleus along a spiral path
• B there must be infinite number of orbits
• C both (a) and (b)
• D None of (a) and (b)

#### Question - 5

Choose CORRECT statement

• A Rutherford's scattering experiment proves the existence of positively charged nucleus
• B The trijectory of a scattered alpha-particle is a hyperpola
• C According to Maxwell's classical theory of electro-magnetic theory, the Rutherford model of atom is unstable
• D ALL OF THE ABOVE

#### Question - 6

Choose INCORRECT statement :

• A The nuclear atomic model was first proposed by J.J Thomson
• B The nuclear atomic model was first proposed by E.Rutherford
• C The shape of electron orbits proposed by Rutherford is circular
• D According to classical theory the proposed circular path of an electron in Rutherford atom will be spiral

#### Question - 7

Rutherford's alpha-particle scattering experiment gave experimental information about

• A the charge on alpha-particle
• B the size of atom
• C the size of nucleus
• D the force between alpha-particle and proton in the nucleus

#### Question - 8

The size of atom is nearly equal to

• A 1 nm
• B 1 micron
• C $1\dot { A }$
• D 1 fermi

#### Question - 9

An electron revolves round the nucleus of charge Ze. In order to excite the electron from the state n =2 to n =3, the energy required is 47.2 eV. The value of Z is

• A 3
• B 2
• C 5
• D 4

#### Question - 10

The ionisation energy of hydrogen is 13.6 eV. Following Bohr's theory, the energy corresponding to a transition between the 3rd and the 4th orbit is

• A 3.4 eV
• B 1.51 eV
• C 0.85 eV
• D 0.66 eV