Question 3 :
Almost the entire mass of an atom is concentrated in the :<br/>
Question 4 :
Who said that cathode rays consist of negatively charged particles ?
Question 7 :
The definitive experiments with cathode-ray tubes were done by ______ in 1879.
Question 16 :
If an atom contains one electron and one proton, what charge will it carry?
Question 17 :
In which of the following transformations, the $\beta $-particles are emitted?
Question 18 :
The cathode rays tube experiments carried out by J.J. Thomson demonstrated that :
Question 19 :
___________ said that cathode rays consist of negatively charged particles and these were named as electrons.
Question 21 :
Oxygen consists of isotopes ${{\text{O}}^{16}}\,$,${{\text{O}}^{17}}\,$ and ${{\text{O}}^{18}}\,$ carbon consists of isotopes of ${{\text{C}}^{{\text{12}}}}$ and ${{\text{C}}^{{\text{13}}}}$ Total number of ${\text{C}}{{\text{O}}_2}$ molecules possible are
Question 22 :
Goldstein's work with anode rays of $H^+$ was apparently the first observation of the :
Question 25 :
An atom of silicon has a mass number of $29$. How many neutrons does it have?  
Question 27 :
Goldsteins experiments which involved passing high voltage electricity through gases at very low pressure resulted in the discovery of:
Question 29 :
By changing the metal electrodes and gas inside the cathode ray tube,
Question 30 :
During the transformation of $_{ c }^{ a }{ X }$ to $_{ d }^{ b }{ Y }$, the number of $\beta $-particles emitted are
Question 33 :
Proton is formed by the loss of electron from which atom/ion?
Question 35 :
Which of the following is true for mass and charge of proton?
Question 40 :
Electrons are the kind of particles which revolve around the nucleus.
Question 41 :
Which of the following is true for mass and charge of electron?
Question 44 :
Compared to the mass of lightest nucleus the mass of an electron is only:<br>
Question 47 :
State whether the given statement is true or false:<br/>Nucleons are particles present in the nucleus of an atom.
Question 49 :
The mass of proton is_____  times the mass of an electron.
Question 50 :
It was known by 1900 that the atom was not a............. , ................particle but contained at least one sub-atomic particle the electron identified by J.J. Thomson. 
Question 56 :
An electron in the hydrogen atom is excited from $1^{st}$ orbit to $5^{th}$ orbit. Find the change in energy of the electron in eV:
Question 60 :
Which of the following is not a postulate given by Rutherford?
Question 61 :
Cathode rays are a stream of fast moving particles that travel in random directions.
Question 63 :
Which of the following is correct for cathode rays in discharge tube?
Question 65 :
The atomic weight of an element is $23$ and its atomic number is $11$. The number of proton, electrons and neutrons respectively, present in the atom of the element are
Question 66 :
Assertion: Cathode rays get deflected towards the negative plate of electric field.
Reason: Cathode rays are negatively charged.
Question 67 :
Assertion: Cathode rays are deflected towards positive plate in an electric field.
Reason: These consist of negatively charged particles.
Question 68 :
The ratio of the "e/m" (specific charge ) values of a electron and an $\alpha- $ particle is :
Question 72 :
An atom of an element has 11 protons, 11 electrons, and 12 neutrons. The atomic mass of the atom is:
Question 73 :
State True or False.<br/>J.J. Thomson's atomic model could not justify the shielding of electrons from positive charges.
Question 75 :
Assertion: $\alpha-$ rays have greater ionizing power than $\beta-$ rays.
Reason: $\alpha-$ particles carry two unit positive charge while $\beta-$ particles carry only one unit negative charge.
Question 78 :
A neutral atom of an element has a nucleus with nuclear charge $11$ times and mass $23$ times that of hydrogen. Find the ratio of no. of electrons to protons present in its stable ion.
Question 80 :
The increase order for the value of $e/m$ (charge to mass ratio) for electron $(e)$, proton $(p)$; neutron $(n)$ and alpha particle $(\alpha)$ is:
Question 83 :
Assertion: A beam of electrons deflects more than a beam of $\alpha$ -particles in an electric field.
Reason: Electrons possess negative charge while $\alpha$ - particles possess positive charge.
Question 84 :
The cathode rays tube experiments carried out by J.J. Thomson demonstrated that:<br/>
Question 89 :
Tick the appropriate answer.<br/>In $1908,$ R A Millikan found the charge of an electron to be
Question 90 :
The subatomic particle which increases or decreases in an atom during the chemical reaction is(are) ________. 
Question 91 :
Assertion: Cathode rays get deflected towards the negative plate of electric field.
Reason: Cathode rays are negatively charged known as electrons.
Question 92 :
Which experiment is responsible for finding out the charge on an electron?
Question 93 :
In $\beta$-emission from a radioactive substance, an electron is ejected from:
Question 96 :
The values of charge on the oil droplets experimentally observed were $-1.6\times 10^{-19}, -2.4\times  10^{-19}$ and $-4\times  10^{-19}$ coulomb. The value of the electronic charge, indicated by these results is
Question 97 :
Through the body of every person, millions of tiny particles pass through silently every second. What are these particles?
Question 100 : Match the values of column II with column I and mark the appropriate choice.<br><table class="wysiwyg-table"><tbody><tr><td></td><td>Column I</td><td></td><td>Column II</td></tr><tr><td>(A)</td><td>Mass of electron</td><td>(i)</td><td>$1.673\times 10^{-27}$ kg</td></tr><tr><td>(B)</td><td>Mass of proton</td><td>(ii)</td><td>$-1.602\times 10^{-19}$ C</td></tr><tr><td>(C)</td><td>Charge of electron</td><td>(iii)</td><td>$9.1\times 10^{-31}$Kg</td></tr><tr><td>(D)</td><td>e/m for an electron</td><td>(iv)</td><td>$1.76\times 10^8 $C/g</td></tr></tbody></table>
Question 105 :
Assertion: The characteristics of cathode rays do not depend upon the material of electrodes and the nature of the gas present in the cathode ray tube.
Reason: Cathode rays consist of negatively charged particles, called electrons.
Question 106 : Match the column- I with Column - II and select the correct answer:<br/><table class="wysiwyg-table"><tbody><tr><td>Column - I</td><td>Column -II</td></tr><tr><td>(I) Curie</td><td>A. $10^6 \, dis \, sec^{-1}$</td></tr><tr><td>(II) Rutherford</td><td>B. $3.7 \times 10^{10} \, dis\, sec^{-1}$</td></tr><tr><td>(III) Becquerel</td><td>C. 1 dis $sec^{-1}$</td></tr></tbody></table>
Question 107 :
Assertion: e/m ratio in case of anode ray experiment is different for different gases.
Reason: The ion of gases formed after the ejection of electron are different if gas is different.
Question 108 :
The mass and charge of one mole of electrons, respectively is:
Question 109 :
Among the following, the correct statement about cathode ray discharge tube is: 
Question 110 :
In an oil drop experiment, the following charges (in arbitary units) were found on a series of oil droplets:<br/>2.30 $\times$ 10$^{-15}$, 6.90 $\times$ 10$^{-15}$, 1.38 $\times$ 10$^{-14}$<br/>5.75 $\times$ 10$^{-15}$, 3.45 $\times$ 10$^{-15}$, 1.96 $\times$ 10$^{-14}$<br/>The magnitude of charge on the electron (in the same unit) is:
Question 111 :
A beam of some kind of particle of velocity $2\times {10}^{7}m/s$ is scattered by a gold $(z=79)$ foil. Find specific charge of this particle (charge/mass) if the distance of closest approach is $7.9\times {10}^{-14}m$.
Question 112 :
The oil drop experiment by R.A. Mulliken was performed to find :
Question 113 :
If the mass of electron is doubled, the speed of electron revolving around $Li^{2+}$ nucleus will ________
