Question:
(a) What are cathode rays ? What is the nature of charge on cathode rays ?
(b)Explain how, cathode rays are formed from the gas taken in the discharge tube.
(c)What conclusion is obtained from the fact that all the gases form cathode rays ?
Answer:
Streams of minute particles were given out by the cathode (negative electrode).These streams of particles are called cathode rays (because they come out of cathode).The mass and charge of the cathode ray particles does not depend on the nature of gas taken in the discharge tube.(b)The gas taken in the discharge tube consists of atoms,and all the atoms contain electrons.When high electrical voltage is applied,the electrical energy pushes out some of the electrons from the atoms of the gas.These fast moving electrons form cathode rays.(c)the formation of cathode rays shows that one of the subatomic particle present in all the atoms is the negatively charged 'electron'.
Structure of the Atom
Q 1.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 2.
Who discovered electrons?
Q 3.
What are cathode rays?
Q 4.
If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?
Q 5.
Write the limitations of J.J. Thomson's model of an atom.
Q 6.
What is the mass of proton as compared to electron?
Q 7.
Who discovered protons?
Q 8.
Fill in the blanks :
The total number of protons and neutrons in the nucleus of an atom is called its __________.
Q 9.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 10.
Fill in the blanks :
An atom has mass number 27 and atomic number 13. The atom has _________ electrons, _____ protons and _______ neutrons.
Q 11.
Who discovered neutrons?
Q 12.
Fill in the blanks :
The mass number of an atom is equal to the number of ________ in its nucleus.
Q 13.
Fill in the blanks :
The maximum number of electrons that can be accommodated in K-shell are _______.
Q 14.
What are ?-particles?
Q 15.
Fill in the blanks :
The fundamental sub-atomic particle called neutron was discovered by ___________.
Q 16.
Fill in the blanks :
The _________ of an atom is dense, small in size and is positively charged.
Q 17.
Name the fundamental particle not present in the nucleus of hydrogen atom
Q 18.
Fill in the blanks :
Mass of a proton is __________ times the mass of an electron.
Q 19.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 20.
State the location of electrons, protons and neutrons in an atom.
Q 21.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 22.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 23.
What is mass number?
Q 24.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 25.
(a) Describe the Rutherford's model of an atom. State one drawback of Rutherford's model of the atom.
(b) The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it ? What is the atomic number of the element ?
Q 26.
What name is given to the pair of atoms such as
N and
N ?
Q 27.
What are the limitations of Rutherford’s model of the atom?
Q 28.
Fill in the blanks :
__________ electrons are located in the outermost shell of an atom.
Q 29.
Who discovered X-Rays?
Q 30.
What were the observations of Rutherford's ?-scattering experiment?
Q 31.
Fill in the blanks :
Anode rays are also called ___________.
Q 32.
What is the electronic configuration of a hydrogen atom
Q 33.
Fill in the following blanks
Atomic
number | Mass number | Protons | Neutrons | Electrons | Symbol |
|---|
| 10 | 22 | ....... | ........ | ....... | ........ |
Q 34.
State one use of radioactive isotopes in industry.
Q 35.
Describe briefly Thomson's model of an atom.
Q 36.
What is the maximum number of electrons that can go into the N shell of an atom ?
Q 37.
Name the particles which actually determine the mass of an atom.
Q 38.
What is the positive charge on the nucleus of an atom due to ?
Q 39.
Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.
Q 40.
Name the radioactive isotope which is used in the treatment of cancer.
Q 41.
What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?
Q 42.
Complete the following statements :
(a) Magnesium has 2 valence electrons in the......... shell.
(b)The valency of nitrogen in N2 molecule is........
(c)Isotopes have different mass numbers because their nuclei contain different number of........
(d) Some boron atoms have mass number 10 and some have mass number 11. These boron atoms with different mass numbers are called............
Q 43.
What are isobars ? Explain with an example.
Q 44.
Who is known as 'Father of Nucleus Physics'?
Q 45.
Name the shell of an atom which can accommodate a maximum of
(a) 2 electrons (b) 18 electrons
Q 46.
How does a proton differ from an electron ?
Q 47.
What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?
Q 48.
Write a short note on Nucleus.
Q 49.
Fill in the blanks :
Atoms are made up of __________, ___________ and __________.
Q 50.
Fill in the blanks :
_______ are atoms having the same mass number but different atomic numbers.
