Physics : Radioactivity

 PHYSICS – 4

MODER PHYSICS

ATOMIC STRUCTURE:

1) Atom of an element ,  is electrically _________

Ans : neutral

2) The smallest unit of element, which carries all the properties of the  element is called an _______ 

Ans : atom

3) Who discovered electrons?

Ans : J J Thomson

4) The electrons in an atom revolve around the nucleus in circular orbits just like ______ revolve around  the  Sun.

Ans : planets

5) Rutherford atomic model consists of ________ massive nucleus at the centre with electrons revolving round it.

Ans: positively charged

6) The electron has a _______  energy in a stationary orbit.

Ans: definite

7) If an electron jumps from lower stationary orbit to higher,  energy  is ______

Ans : absorbed

8) When an electron jumps from higher stationary orbit to lower energy orbit, energy is _____

Ans : released

9) The space between electron and proton is _______

Ans : vacuum

10) Proton is a _________

Ans : positively charged particle

11) Who discovered protons ?

Ans : Rutherford and Goldstein

12) The alfa – particle is a _______ charged particle

Ans : positively

ATOMIC NUMBER, ATOMIC MASS AND MASS DEFECT : 

1) Atomic number of an element indicates the number of _______ in an atom

Ans : protons or electrons

2) AMU stands for _____

Ans : Atomic Mass Unit

3) Mass Number is the sum of number of protons and number of _________

Ans: Neutrons

4) Neutron is discovered by ____ in 1932

Ans : Chadwick

5) Neutron is  electrically ________

Ans : neutral

6) The number of protons in an atom is defined as ____________

Ans : atomic number

7) The mass of an atom is measured in ______

Ans : atomic mass unit or a.m.u.

8) ________ is the difference between the sum of the individual masses of constituents in a nucleus and the mass of the nucleus itself.

Ans : Mass defect

9) According to Einstein mass energy relation ____________ 

Ans :  E = Δmc2

10) Atomic number is also called ______ number

Ans : proton

11) Atomic number is denoted by _________

Ans : Z

12) Protons are also equal to the number of ______ in a neutral atom

Ans : electrons

13) The mass of one proton is ___________

Ans : 1.0078 a.m.u

14) The mass of one neutron is __________

Ans : 1.0087 a.m.u.

15) An isotope which is used in the determination of age of fossils is _________

Ans : Radio Carbon 

 16) Mass defect =   ______________

Ans : ( sum of individual masses of constituents – actual mass of the nucleus)

17) The relation between mass and energy conversion was postulated by _______

Ans : Albert Einstein

18) Oxygen atom contains _________

Ans : 8 protons and 8 neutrons

RADIOACTIVITY:  

1) The alpha – particle is a __________ charged particle.

Ans : positively

2) The mass of beta particle is the same as the mass of ________

Ans : electron

3) Isobars are the elements with same mass _______

Ans : number

4) Ionising power is highest in the case of ________

Ans : alpha – particles

5) Penetrating capacity is highest for _______

Ans : gamma-rays

6) The electromagnetic radiation observed in radio activity is ________

Ans : gamma – rays

7) Radioactivity was discovered by _______

Ans : Henry Bequerel

8) Fluorescence is the ability of certain substances to transform incident ultraviolet radiation into ________ light.

Ans : visible

9) Uranium ore is _____

Ans : Pitch blend 

10) Alpha, beta, gamma radiations are emitted by ________

Ans: radioactive nuclei

11) An alpha particle is consists of two protons and two ________

Ans : neutrons

12) The speed of alpha particles in air is ________

Ans : 10 7 m/s

13) Beta particles are electrons originating in the _______

Ans: nucleus

14) Gamma rays travel with the speed of ________

Ans : light

15) Gamma rays are unaffected by __________

Ans : electric and magnetic field

16) Gamma – rays can easily destroy human _______

Ans : cells

17) Gamma rays are used to kill cancer cells in the treatment of ______

Ans : Cancer

18) Radon is an ____ gas

Ans: inert

19) Alfa particle is _____ charges particle.

Ans : positively

20) When alfa particles is emitted, the atomic number of an atom increases _______

Ans : 2 units

21) Moderator in a nuclear reactor reduces the _____ of the neutrons.

Ans : speed

22) Fusion reactions take place in  ________

Ans : Stars

23) Uranium-235  is an isotope used in the determination of ______

Ans : age of rocks

24) Carbon-14  is an isotope used in the determination of  ______

Ans: age of fossils

25) The process of transformation of one element into another artificial means of bombarding it with high energy particles is known as _________

Ans : artificial transmutation

26) Artificial transmutation was discovered by _______

Ans : Rutherford

27) Functioning of the Thyroid gland can be tested by _______

Ans : 131- Iodine isotope

28) ______is  process in which a heavy nucleon, when bombarded with neutrons, splits into two nuclei of nearly equal mass with the release of enormous amount of energy.

Ans : Nuclear fusion

29) Nuclear fission was discovered by _____

Ans : Otto Hahn

30) An average of _____ of energy is released per fission of an Uranium atom.

Ans : 200 MeV

31) A ______ is a series of nuclear fissions whereby the neutrons produced in each fission cause additional fissions.

Ans : Chain Reaction

32) The material that slows down the neutrons in a nuclear reactor is called as __________  

Ans: moderator

33) An uncontrolled chain reaction occurs in __________

Ans : atom bomb     

34) In nuclear reactor control rods are made of ________

Ans : Cadmium or boron

35) ___________ is a reaction in which light nuclei are combined together to form a heavier product nucleus with the use release of enormous amount of energy.

Ans : Fusion

36) A radioactive isotope is called a radio _____

An s: isotope

37) Radioactive cobalt is used to detect internal ______ in the cast material

Ans : flaws

38) Radio carbon dating is done by estimating in the specimen by the ratio of  ______

An s: C-14 / C-122

39) The radio isotope used to cure cancer is _______

Ans : Cobalt isotope

40) In U-235 chain fission, chain is installed by a ______

Ans : neutron

41) Nuclear fusion is opposite to ______

Ans : nuclear fission

42) Radio isotopes formed by nuclear transmutation are rarely found in nature because they have very short _____ period.

Ans : half life

43) The fusion reactions require high temperatures, are also called _______

Ans : thermo nuclear reactions.              

44) The _____ cycles are responsible for energies of the stars like the Sun.

Ans : proton                                                                                                         

45) The principle of hydrogen bomb is _____________

Ans : uncontrolled fusion reaction

46) The material that slows down the neutrons in a nuclear reactor is called ______ 

Ans : moderator

47) The fuel used in a nuclear reactor is _____________

Ans : Uranium – 235

48) The projectiles used in a fission of U-235 are ________

Ans : neutrons

49) The relation between mass and energy was postulated by _______

Ans : Albert Einstein

50) The reason for using cadmium rods in nuclear reactor is ________

Ans : to absorb neutrons

51) The time taken by radioactive element to disintegrate completely ________

Ans : infinite

52) In a nuclear reactor cadmium is used as a _________

Ans : Control Rod

53) In a nuclear reactor, graphite is used as ___________

Ans : moderator

54) In a nuclear reactor entire region of a fuel elements is known as ________

Ans : Reactor core