1.

The “magic numbers” for atoms are

• numbers of electrons that confer atomic stability.
• numbers of protons and/or neutrons that confer nuclear stability.
• n/p ratios that confer nuclear stability.
• atomic masses that confer nuclear stability.
• atomic masses that indicate fissile isotopes.

2.

The actual mass of a 37Cl atom is 36.966 amu. Calculate the mass defect (amu/atom) for a 37Cl atom.

• 0.623 amu
• 0.388 amu
• 0.263 amu
• 0.341 amu
• none of these

3.

The mass defect for an isotope was found to be 0.410 amu/atom. Calculate the binding energy in kJ/mol of atoms. (1 J

= 1 kg m2/s2)

(a) 3.69 x 1010 kJ/mol

(b) 1.23 x 1020 kJ/mol

(c) 3.69 x 1013 kJ/mol

(d) 1.23 x 103 kJ/mol

(e) 1.23 x 1023 kJ/mol

4.

Calculate the binding energy per nucleon (in units of MeV) for 9Be, for which the atomic mass is 9.01219 amu. Particle masses in amu are: proton = 1.007277; neutron = 1.008665; electron = 0.0005486. Conversion factor for E = mc2 is 931 MeV/amu.

• 6.46 MeV
• 6.33 MeV
• 6.23 MeV
• 11.39 MeV
• 56.93 MeV

5.

Which isotope below has the highest nuclear binding energy per gram? No calculation is necessary.

• 4He
• 16O
• 32S
• 55Mn
• 238U

6.

Which of the following statements is incorrect?

• Mass defect is the amount of matter that would be converted into energy if a nucleus were formed from initially separated protons and neutrons.
• Nuclear binding energy is the energy released in the formation of an atom from subatomic particles.
• Nuclei with highest binding energies are the most stable nuclei.
• Einstein postulated the Theory of Relativity in which he stated that matter and energy are equivalent.
• Mass number is the sum of all protons and electrons in an atom.

7.

A positron has a mass number of         , a charge of           , and a mass equal to that of a(an)                                                          .

• 0, 1+, proton
• 1, 2+, proton
• 0, 1+, electron
• 1, 2+, electron
• 0, 0, proton

8.

Emission of which one of the following leaves both atomic number and mass number unchanged?

• positron
• neutron
• alpha particle
• beta particle

9.

Which type of radiation is the least penetrating?

(a) alpha                                            (b) beta

• gamma
• x-ray
• neutron

10.

A radioisotope of argon, 35Ar, lies below the “band of stability: (n/p ratio too low). One would predict that it decays via

.

• neutron emission
• beta emission
• positron emission
• alpha emission
• fission

11.

A Geiger-Muller tube is a           .

• gas ionization detector
• cloud chamber
• fluorescence detector
• spectrophotometer
• photographic detector

12.

The half life of 231Pa is 3.25 x 104 years. How much of an initial 10.40 microgram sample remains after 3.25 x 105 years?

• 0.0102 micrograms
• 0.240 micrograms
• 2.18 micrograms
• 0.0240 micrograms
• 1.04 micrograms

13.

Consider the case of a radioactive element X which decays by electron (beta) emission with a half-life of 4 days to a stable nuclide of element Z. Which of the following statements is CORRECT?

• After 8 days the sample will consist of one-fourth element Z and three-fourths element X.
• Element Z will weigh exactly the same as element X when decay is complete (weighed to an infinite number of significant figures).
• 2.0 g of element X is required to produce 1.5 g of element Z after 8 days (to 2 significant figures).
• If element X as an atomic number equal to n, then element X has an atomic number equal to n-1.
• None of the above.

14.

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20 minutes. What fraction of the initial number of C-11 atoms in a sample will have decayed away after 80 minutes?

(a) 1/16

(b) 1/8

(c) 1/4

(d) 7/8 (e) 15/16

15.

How old is a bottle of wine if the tritium (3H) content (called activity) is 25% that of a new wine? The half-life of tritium is 12.5 years.

• 1/4 yr
• 3.1 yr
• 25 yr
• 37.5 yr
• 50 yr

16.

A Geiger counter registered 1000 counts/second from a sample that contained a radioactive isotope of polonium. After

5.0 minutes, the counter registered 281 counts/second. What is the half-life of this isotope in seconds?

(a) 87

(b) 110

(c) 164

(d) 264 (e) 2.18

17.

The 14C activity of some ancient Peruvian corn was found to be 10 disintegrations per minute per gram of C. If present-day plant life shows 15 dpm/g, how old is the Peruvian corn? The half-life of 14C is 5730 years.

• 1455 years
• 1910 years
• 3350 years
• 3820 years
• 9080 years

18.

Which of the following describes what occurs in the fission process?

• A heavy nucleus is fragmented into lighter ones.
• A neutron is split into a neutron and proton.
• Two light nuclei are combined into a heavier one.
• A proton is split into three quarks.
• A particle and anti-particle appear in an area of high energy density.

19.

Which of the following statements about nuclear fission is always correct?

• Very little energy is released in fission processes.
• Nuclear fission is an energetically favorable process for heavy atoms.
• Due to its instability, 56Fe readily undergoes fission.
• In fission reactions, a neutron is split into a proton and an electron.
• All nuclear fission reactions are spontaneous.

20.

Which one of the following would be most likely to undergo thermonuclear fusion?

• 2H
• 4He
• 56Fe
• 141Ba
• 235U

21.

Which one of the following statements about nuclear reactions is false?

• Particles within the nucleus are involved.
• No new elements can be produced.
• Rate of reaction is independent of the presence of a catalyst.
• Rate of reaction is independent of temperature.
• They are often accompanied by the release of enormous amounts of energy.

22.

Complete and balance the following equation. The missing term is        .

239Pu + alpha particle + neutron

• 115Ag
• 106Rh
• 235U
• 233Pa
• 242Cm

23.

When 59Cu undergoes positron emission, what is the immediate nuclear product?

• 59Ni
• 58Ni
• 58Cu
• 59Zn
• 58Zn

24.

As a result of the process of electron capture (“K-capture”) by 211At, the new isotope formed is:

• 210At
• 212At
• 211Po
• 211Rn
• 207Bi

25.

When 235U is bombarded with one neutron, fission occurs and the products are three neutrons, 94Kr, and                                                                                                                                                               .

• 139Ba
• 141Ba
• 139Ce
• 139Xe
• 142I

1. (b) 2. (d) 3. (a) 4. (a) 5. (d) 6. (e) 7. (c) 8. (d) 9. (a) 10. (c) 11. (a) 12. (a) 13. (c) 14. (e) 15. (c) 16. (c) 17. (c) 18. (a) 19. (b) 20. (

a) 21. (b) 22. (e) 23. (a) 24. (c) 25. (a)

SET – II

1. J.J. Thomson
1. Henry Becquerel
1. Rutherford
2. Have same atomic numbers but different atomic masses
• Isotope
• Atom
• None of these
3. When a radioactive substance is subjected to a vacuum, the rate of disintegration per second
• Increases only if the products are gaseous
• Increase considerably
• Decreases
• Is not affected
• Isotope
• Atom
• None of these
5. Which one of the following are Gamma rays.
• Low energy waves
• High energy protons
• High energy electron
• High energy electromagnetic waves
6. Which one of the following has no charge?
• Gamma rays
• Beta rays
• Alpha rays
• Cathode rays
7. Which of the following is the smallest particle of an element that retains the properties of that element?
• Isotope
• Atom
• None of these
8. Hydrogen bomb is based on the phenomenon of
• Nuclear explosion
• Chemical reaction
• Nuclear fusion
• Nuclear fission
9. which of the following Uranium gives stable isotope of
• Krypton
• Polonium
1. The nucleus of radioactive element possesses

SET – IV

(a) Low binding energy (b) High binding energy (c) Zero binding energy (d) High potential energy Sol: a

• Nuclear energy is based on the conversion of

(a) Protons into neutrons (b) Mass into energy (c) Neutrons into protons (d) Uranium into radium Sol: b

• Positron has nearly the same weight as that of

(a) Alpha-particle (b) Proton (c) Neutron (d) Electron Sol: d

• Hydrogen and deuterium differ in

(a) Reactivity with oxygen (b) Reactivity with chlorine (c) Melting point (d) Reducing action

Sol: (c) Isotopes of an element have similar chemical properties but different physical properties.

• A nuclear reaction must be balanced in terms of

(a) Only energy (b) Only mass (c) Mass and energy (d) None of these

Sol: (c) A nuclear reaction must be balanced in terms of mass and energy

• Positronium is the name given to an atom-like combination formed between (a) A positron and a proton (b) A positron and a neutron (c) A positron and -particle (d) A positron and an electron

Sol: d Sol: (b) Equate atomic no. and mass no.

• The introduction of a neutron into the nuclear composition of an atom would lead to a change in

(a) The number of the electrons also (b) The chemical nature of the atom (c) Its atomic number (d) Its atomic weight Sol: (d) Mass number increases by one unit.

• Neutrino has

(a) Charge +1, mass 1 (b) Charge 0, mass 0 (c) Charge – 1, mass 1 (d) Charge 0 , mass 1 Sol: (b) Neutrino have no mass and no charge and thus known as ghost particles.

• Formation of nucleus from its nucleons is accompanied by

(a) Decrease in mass (b) Increase in mass (c) No change of mass (d) None of them Sol: (a) Due to mass decay.

1. A particle having the same charge and 200 times greater mass than that of electron is

(a) Positron (b) Proton (c) Neutrino (d) Meson

Sol: (d) Mesons (m) have 200-300 times mass of electron and + ve, 0 or – ve charges.

1. The nucleus of an atom is made up of X protons and Y neutrons. For the most stable and abundant nuclei

(a) X and Y are both even (b) X and Y are both odd (c) X is even and Y is odd (d) X is odd and Y is even Sol: (a) Even-Even are most stable Odd- Odd are most unstable

1. Atom A possesses higher values of packing fraction than atom B. The relative stabilities of A and B are

(a) A is more stable than B (b) B is more stable than A (c) A and B both are equally stable (d) Stability does not depend on packing fraction

Sol: (b) The atom which have lower value of packing fraction is stable.

1. How many neutrons are present in the nucleus of Ra (a) 88 (b) 226 (c) 140 (d) 138

Sol: (d)

1. In a nuclear explosion, the energy is released in the form of

(a) Kinetic energy (b) Electrical energy (c) Potential energy (d) None of these Sol: (d) Nuclear reactions involves exchange of nuclear energy.

1. Nuclear reactivity of Na and is same because both have (a) Same electron and proton (b) Same proton and same neutron

(c) Different electron and proton (d) Different proton and neutron

Sol: (b) Nuclear reactivity depends upon the number of protons and neutrons.

1. Which of the following is the heaviest metal (a) Hg (b) Pb (c) Ra (d) U Sol: d
2. a-particles can be detected using

(a) Thin aluminum sheet (b) Barium sulphate (c) Zinc sulphide screen (d) Gold foil

Sol: (c) Rutherford first of all used zinc sulphide (ZnS) as phosphor in the detection of a-particles.

1. The a-particle is identical with

(a) Helium nucleus (b) Hydrogen nucleus (c) Electron (d) Proton Sol: (a) a-particle is identical with helium nucleus

1. a-rays have

(a) Positive charge (b) Negative charge (c) No charge (d) Sometimes positive charge and sometimes negative charge Sol: (a) a-rays are positively charged, b-rays are negatively charged, g-rays carry no charge.

• X-rays are produced due to

(a) Bombarding of electrons on solids (b) Bombarding of a-particle on solids (c) Bombarding of g-rays on solids (d) Bombarding of neutron on solids

Sol: a

• There exists on g-rays

(a) Positive charge (b) Negative charge (c) No charge (d) Sometimes positive charge, sometimes negative charge Sol: (c) g-rays carry no charge.

• The radiations from a naturally occurring radio element, as seen after deflection in a magnetic field in one direction, are

(a) Definitely a-rays (b) Definitely b-rays (c) Both a and b-rays (d) Either a or b-rays Sol: (d) Due to it’s nature.

• The element californium belongs to the family of

(a) Actinide series (b) Alkali metal family (c) Alkaline earth family (d) Lantanide series Sol: (a) Cf – 98 belongs to actinid series.

• Which of the following is not deflected by magnetic field

(a) Deuteron (b) Positron (c) Proton (d) Photon Sol: (d) Photons are not carry any charge.

(a) Stable electronic configuration (b) Unstable electronic configuration (c) Stable nucleus (d) Unstable nucleus Sol: (d) Radioactivity is characteristic property of unstable nucleus.

• Radioactive disintegration differs from a chemical change in being

(a) An exothermic change (b) A spontaneous process (c) A nuclear process (d) A unimolecular first order reaction Sol: (c) Chemical change is extra nuclear phenomenon.

• When a radioactive element emits an electron the daughter element formed will have

(a) Mass number one unit less (b) Atomic number one unit less (c) Mass number one unit more (d) Atomic number one unit more

Sol: (d)

• During a b–decay the mass of the atomic nucleus

(a) Decreases by one unit (b) Increases by one unit (c) Decreases by two units (d) Remains unaffected Sol: (d) During b–decay atomic mass is unaffected while atomic no. increases by one unit.

• A nuclide of an alkaline earth metal undergoes radioactive decay by emission of the a– particles in succession. The group of the periodic table to which the resulting daughter element would belong

(a) Gr.14 (b) Gr.16 (c) Gr.4 (d) Gr.6

Sol: (b)

• Group displacement law was given by

(a) Becquerel (b) Rutherford (c) Soddy and Fajan (d) Madam Curie Sol: (c) It is also called Soddy and Fajan rule.

• A certain nuclide has a half-life period of 30 minutes. If a sample containing 600 atoms is allowed to decay for 90 minutes, how many atoms will remain

(a) 200 atoms (b) 450 atoms (c) 75 atoms (d) 500 atoms Sol: (c) .

• If the quantity of a radioactive element is doubled, then its rate of disintegration per unit time will be

(a) Unchanged (b) Reduced to half (c) Increased by root2 times (d) Doubled Sol: (d) Rate = l× number of atoms.

• The atomic number of a radioactive element increases by one unit in

(a) Alpha emission (b) Beta emission (c) Gamma emission (d) Electron capture Sol: (b)

• When a Beta-particle emits from the atom of an element, then

(a) Atomic number increases by two units (b) Atomic number increases by three units (c) Atomic number decreases by one unit

(d) Atomic number increases by one unit Sol: (d)

• Half-life period of a metal is 20 days. What fraction of metal does remain after 80 days (a) 1 (b) 1/16 (c) 1/4 (d) 1/8

Sol: (b)

• A radioactive element decays at such a rate that after 15 minutes only 1/10 of the original amount is left. How many more minutes will be needed when only 1/100 of the original amount will be left

(a) 1.5 minutes (b) 15.0 mintues (c) 16.5 minutes (d) 30 minutes Sol: d

• A radioactive isotope having a half-life of 3 days was received after 12 days. It was found that there were 3 gm of the isotope in the container. The initial weight of the isotope when packed was

(a) 12 gm (b) 24 gm (c) 36 gm (d) 48 gm Sol: (d) \.

• C14 is radioactive. The activity and the In a radioactive decay, an emitted electron comes from

(a) Nucleus of the atom (b) Inner orbital of the atom (c) Outermost orbit of the atom (d) Orbit having principal quantum number one

Sol: (a) In nucleus electrons formed by the following decay.

• If 2gm of a radioactive isotope has a half-life of 20 hr, the half-life of 0.5gm of the same substance is

(a) 20 hr (b) 80 hr (c) 5 hr (d) 10 hr

Sol: (a) Half-life period is a characteristic of radioactive isotope which is independent of initial concentration.

• The half-life of a radioactive element is 6 months. The time taken to reduce its original concentration to its 1/16 value is

(a) 1 year (b) 16 years (c) 2 years (d) 8 years Sol: (c)

• The phenomenon of radioactivity arises from the

(a) Binary fission (b) Nuclear fusion (c) Stable nuclei (d) Decay of unstable nuclei Sol: d

• The first artificial disintegration of an atomic nucleus was achieved by

(a) Geiger (b) Wilson (c) Madame curie (d) Rutherford (e) Soddy Sol: D

• Radioactive carbon dating was discovered by

(a) W.F. Libby (b) G.N. Lewis (c) J. Willard Gibbs (d) W. Nernst

Sol: (a) For studies on carbon dating, W. F. Libby was awarded a Nobel prize.

• To determine the masses of the isotopes of an element which of the following techniques is useful

(a) The acceleration of charged atoms by an electric field and their subsequent deflection by a variable magnetic field (b) The spectroscopic examination of the light emitted by vaporised elements subjected to electric discharge (c) The photographing of the diffraction patterns which arise when Xrays are passed through crystals (d) The bombardment of metal foil with alpha particles

Sol: (a) It is the required technique.

• Neutron is used as a

(a) Reducing agent (b) Moderator (c) Tracer (d) In biological programme Sol: C

• Hydrogen bomb is based on the phenomenon of

(a) Nuclear fission (b) Nuclear fusion (c) Nuclear explosion (d) Disintegration Sol: (b) In hydrogen bomb, the following reaction is occur, .

• In the nuclear reactors the speed of the neutrons is slowed down by

(a) Heavy water (b) Ordinary water (c) Zinc rods (d) Molten caustic soda Sol: (a) Heavy water is D2O.

• By which law, energy produced in nuclear reaction is given

(a) Graham’s law (b) Charle’s law (c) Gas Lussac’s Law (d) Einstein’s law Sol: (d) Einstein’s law

• The fuel of atomic pile is

(a) Thorium (b) Sodium (c) Uranium (d) Petroleum Sol: (c) Uranium or Plutonium are atomic fuel.

• Atom bomb is based on the principle of

(a) Nuclear fusion (b) Nuclear fission (c) Radioactivity (d) Fusion and fission both Sol: (b) atom bomb is based on the principal of nuclear fission.

• Who observed that when the nucleus of uranium atom was bombarded with fast moving neutrons, it becomes so very unstable that it is immediately broken into two nuclei of nearly equal mass besides other fragments

(a) J.J. Thomson (b) Chadwick (c) Einstein (d) Hahn and Strassmann

Sol: (d) Hahn and Strassmann discovered the phenomenon of nuclear fission in 1939.

• When a radioactive substance is subjected to vacuum, the rate of disintegration per second

(a) Increases considerably (b) Increases only if the products are gaseous (c) Is not affected (d) Suffers a slight decrease Sol: (c) Rate of disintegration is not affected by environmental conditions.

• Large energy released in an atomic bomb explosion is mainly due to

(a) Products having a lesser mass than initial substance (b) Conversion of heavier to lighter atoms (c) Release of neutrons (d) Release of electrons

Sol: (a) Mass decay occurs.

• Carbon-14 dating method is based on the fact that

(a) Carbon-14 fraction is the same in all objects (b) Carbon-14 is highly insoluble (c) Ratio of carbon-14 and carbon-12 is constant (d) All of these

Sol: (c) A reason for the C-14 dating technique.

• Which of the following statements about radioactivity of an element is incorrect

(a) It is a nuclear property (b) It does not involve any rearrangement of electrons (c) Its rate is affected by change in temperature and/or pressure (d) It remains unaffected by the presence of other element or elements chemically combined with it

Sol: (c) Rate of radioactivity is independent of all external factors.

• Radioactive iodine is being used to diagnose the disease of

(a) Bones (b) Kidneys (c) Blood cancer (d) Thyroid Sol: (d)

• The huge amount of energy which is released during atomic fission is due to (a) Loss of mass (b) Loss of electrons (c) Loss of protons (d) Loss of -particles

Sol: (a) The huge amount of energy released during atomic fission is due to loss of mass.

• The measure of binding energy of a nucleus is the

(a) Mass defect (b) Energy of protons (c) Energy of neutrons (d) Total energy of nucleons Sol: (a) Mass defect is the measure of binding energy of a nucleus.

• The first controlled artificial disintegration of an atomic nucleus was achieved by

(a) Geiger (b) Wilson (c) Cockcroft (d) Rutherford Sol: D

• Artificial radioactivity was first discovered by

(a) Seaberg (b) Rutherford (c) Einstein (d) Irene Curie & Juliot Sol: (d) Irene curie and Juliot studied the artificial radioactivity.

• Artificial transmutation was discovered by

(a) Pauli (b) Rutherford (c) Soddy (d) Curie Sol: B

• – 18 isotope of oxygen will have

(a) 18 protons (b) 9 protons and 9 neutrons (c) 8 neutrons and 10 protons (d) 10 neutrons and 8 protons SOL: (d)

• Isotopes are atoms having the same

(a) Atomic mass (b) Mass number (c) Atomic number (d) Number of neutrons SOL: (c) Isotopes have same atomic number but different mass number.

• Isotopes of an element have

(a) Similar chemical properties but different physical properties (b) Similar chemical and physical properties (c) Similar physical properties but different chemical properties (d) Different chemical and physical properties

SOL: A

• Whose number is common in isotopes

(a) Proton (b) Neutron (c) Proton and neutron (d) Nucleon

SOL: (a) Isotopes differ in number of neutrons but have same number of protons.

• Which property is different for neutral atoms of the two isotopes of the same element

(a) Number of protons (b) Atomic number (c) Number of neutrons (d) None of these SOL: (c) Isotopes differ in mass no. and hence in the number of neutrons.

• The maximum sum of the number of neutrons and protons in an isotope of hydrogen is (a) 4 (b) 5 (c) 6 (d) 3

SOL: (d) there are 1 proton and 2 neutrons.

• Addition of two neutrons in an atom A would

(a) Change the chemical nature of A (b) Produce an isobar of A (c) Produce an isotope of A (d) Produce another element SOL: (c)

• Atomic weight of the isotope of hydrogen which contains 2 neutrons is the nucleus would be

(a) 2 (b) 3 (c) 1 (d) 4 SOL: (b) Atoms of different elements having different atomic no. but same mass no. are called isobars.

• Which character is different of the two isotopes of an

(a) Atomic mass (b) Atomic number (c) Number of electrons (d) Number of protons SOL: (a) Isotopes have same atomic number but different mass number.

• Two atoms have the same atomic mass but different atomic numbers. Such atoms are called as

(a) Isotopes (b) Isobars (c) Isomer (d) Isoelectronic

SOL: (b) Atoms of different elements having different atomic no. but same mass no. are called isobars

• An isotope of oxygen has mass number 18. Other isotopes of oxygen will have the same

(a) Mass number (b) Atomic weight (c) Number of neutrons (d) Number of protons SOL: (d) Isotopes differ in number of neutrons but have same number of protons.

• Two nuclei which are not identical but have the same number of nucleons represent

(a) Isotopes (b) Isobars (c) Isotones (d) None of the three

SOL: (b) Atoms of different elements having different atomic no. but same mass no. are called isobars.

• Isotopes differ in

(a) Number of protons (b) Valency (c) Chemical reactivity (d) Number of neutron SOL: (d) Isotopes differ in number of neutrons but have same number of protons.

• The isobars are atoms with the same number of

(a) Protons (b) Neutrons (c) Protons and neutrons (d) Nucleons

SOL: (d) Atoms of different elements having different atomic no. but same mass no. are called isobars.

• Radioactive isotope of hydrogen is

(a) Tritium (b) Deuterium (c) Para hydrogen (d) Ortho hydrogen SOL: (a)

• Isotopes of same elements have the same number of

(a) Protons (b) Neutrons (c) Deutrons (d) None

SOL: (a)Isotopes of same elements have the same number of protons but different number of neutrons

SET – V

Q1: The neutral atoms of all isotopes of the same element contain the same number of                       . neutrons only.                                        Electrons                     Mass numbers                                  Masses

Q2: The atomic number is not changed by which type of radioactive decay?

Beta                                         Gamma

Alpha                                       The atomic number is affected by all forms of radioactive decay Answer: (b) Gamma

Q3: Isotopes of an element have a different number of

Proton                                     Neutron                                                            Electron                                                            atom Answer: (b) Neutron

Q4: Three types of radioactive elements are emitted when unstable nuclei undergo radioactive decay. Which of the following is not one of them

Beta                                                     Gamma

Alpha                                                   delta

Q5: A nuclear fission reaction becoming self-sustaining depends on Electrons                                             Neutrons

Energy                                                 Protons

Q6: Helium nuclei particles are called

Gamma particles                                 Beta particles

Alpha particles                                     No particles that are helium nuclei Answer: (c) alpha particles

Q7: When two atomic nuclei combine it is called as

Chain reaction                                     Nuclear fusion

Nuclear decay                                      Nuclear fission Answer: (b) Nuclear fusion

Q8: The number of protons or atomic number is reduced to 2 by which form of radioactive decay?

Beta-decay                              Gamma decay

Alpha decay                             None of the above Answer: (c) Alpha decay

Q9: Which statement is true for all three types of radioactive emission? They are deflected by electric fields                              They ionise gases

They are completely absorbed by a thin aluminium sheet                                                                                                   They emit light Answer: (b) They ionise gases

Q10: A nuclide of the element plutonium 94 Pu 242. What is the number of neutrons in its nucleus?

242                               336                               148                                           94

1. The atomic mass unit is defined as

a. the mass of a proton.

b. the mass of an electron.

c. the mass of a hydrogen-1 atom.

d. one twelfth the mass of a carbon-12 atom.

2. An element with atomic mass number of 14 and atomic number 6 has how many neutrons?

a. 6

b. 8

c. 14

d. 20

3. Isotopes of an element have nuclei with

a. the same number of protons, but different

numbers of neutrons.

b. the same number of protons, and the same

number of neutrons.

c. a different number of protons, and a

different number of neutrons.

d. a different number of protons, and the

same number of neutrons.

4. If an atom’s atomic number is given by Z, its atomic mass by A, and its neutron number by N, which of the following is correct?

a. N = A + Z

b. N = Z – A

c. N = A – Z

d. None of the above is correct.

5. In a {93/41}Nb nucleus, the number of protons, neutrons, and electrons is

a. 41, 52, 93

b. 41, 52, 52

c. 41, 52, 41

d. 41, 52, 0

6. The binding energy per nucleon

a. increases steadily as we go to heavier

elements.

b. decreases steadily as we go to heavier

elements.

c. is approximately constant throughout the

periodic table, except for very light nuclei.

d. has a maximum near iron in the periodic

table.

7. An alpha particle is also known as

a. an electron.

b. a positron.

c. a helium nucleus.

d. a photon.

8. A beta^- particle is also known as

a. an electron.

b. a positron.

c. a helium nucleus.

d. a photon.

9. The existence of the neutrino was postulated in order to explain

a. alpha decay.

b. gamma emission.

c. beta decay.

d. fission.

10. When an alpha particle is emitted from an unstable nucleus, the atomic mass number of the nucleus

a. increases by 2.

b. decreases by 2.

c. increases by 4.

d. decreases by 4.

e. none of the above.

11. If 4.0X1018 atoms decay with a half-life of 2.3 years, how many are remaining after 3.7 years?

a. 2.5X1018

b. 1.7X1018

c. 1.3X1018

d. 1.1X1018

12. A radioactive sample has a half-life of 5.0 min. What fraction of the sample is left after 20 min?

a. 1/2

b. 1/4

c. 1/8

d. 1/16

13. The half-life of radioactive iodine-137 is 8.0 days. How many iodine nuclei are necessary to produce an activity of 1.0 micro-Ci?

a. 2.9X109

b. 4.6X109

c. 3.7X1010

d. 7.6X1012

14. What happens to the half-life of a radioactive substance as it decays?

a. It remains constant.

b. It increases.

c. It decreases.

d. It could do any of these.

15. The mass of {90/38}Sr is 89.907737 u and the mass of the atom its beta decays to is 89.907151 u. What is the energy released in the decay?

a. 1.2 MeV

b. 112 keV

c. 0.546 MeV

d. 1.8 MeV

1. d

2. b

3. a

4. c

5. d

6. d

7. c

8. a

9. c

10. d

11. c

12. d

13. c

14. a

15. c

`Related Data`