1
MCQ (Single Correct Answer)
Which of the following conclusions could not be derived from Rutherford's $\alpha$-particle scattering experiment?
A
Most of the space in the atom is empty
B
The radius of the atom is about $10^{-10} \mathrm{~m}$ while that of nucleus is $10^{-15} \mathrm{~m}$
C
Electrons move in a circular path of fixed energy called orbits
D
Electrons and the nucleus are held together by electrostatic forces of attraction
2
MCQ (Single Correct Answer)
Which of the following options does not represent ground state electronic configuration of an atom?
A
$1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^8 4 s^2$
B
$1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^9 4 s^2$
C
$1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^{10} 4 s^1$
D
$1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^5 4 s^1$
3
MCQ (Single Correct Answer)
The probability density plots of 1s and 2s orbitals are given in figure.
The density of dots in a region represents the probability density of finding electrons in the region.
On the basis of above diagram which of the following statements is incorrect?
A
$1 s$ and $2 s$ orbitals are spherical in shape
B
The probability of finding the electron is maximum near the nucleus
C
The probability of finding the electron at a given distance is equal in all directions
D
The probability density of electrons for $2 s$ orbital decreases uniformly as distance from the nucleus increases
4
MCQ (Single Correct Answer)
Which of the following statement is not correct about the characteristics of cathode rays?
A
They start from the cathode and move towards the anode
B
They travel in straight line in the absence of an external electrical or magnetic field
C
Characteristics of cathode rays do not depend upon the material of electrodes in cathode ray tube
D
Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube
5
MCQ (Single Correct Answer)
Which of the following statements about the electron is incorrect?
A
It is a negatively charged particle
B
The mass of electron is equal to the mass of neutron
C
It is a basic constituent of all atoms
D
It is a constituent of cathode rays