Previous Year Physics Question Papers (with solutions) of Kerala State Syllabus of Higher Secondary Examinations. Chapter Name: NUCLEI

The half-life of Radon is 3.8 days.
a) Define half-life.
b) Calculate how much of 15mg of Radon will remain after 14.2 days.

(a) In the following nuclear fission reaction, N is the number of neutrons released. What is the value of N?
²³⁵U₉₂ + ¹n₀ --> ⁹⁴Sr₃₈ + ¹⁴⁰Xe₅₄ + N
(b) Complete the following nuclear reaction equation.
⁹Be₄ + ⁴He₂ --> ¹n₀+ -------
(c) Two nuclei have mass number iin the ratio 1: 8. What is the ratio of their nuclear radii?

In a nuclear reactor the chain reaction is carried out under controlled conditions
a) Name the material that used as control rods in a nuclear reactor
b) Average energy of a neutron produced in fission of ²³⁵U₉₂ is .................
c) Write down the reactions involved in the conversion of²³⁸U₉₂ to ²³⁹Pu₉₄ nuclear reactor

Energy generation in stars is due to nuclear fusion
a) How a nuclear fusion is occurred?
b) The energy released in nuclear fission process with uranium is of the order of ........................
c) Three types of radioactive decay occur in nature. Briefly describe them d) State Radio active decay law

(a) Obtain an expression for the number of radioactive nuclei present at any instant in terms of the decay constant and initial number of nuclei
(b) The half-life of radioactive radon is 3.8 days. Find the time during which 1/20 of radon sample will remain undecayed

(a) what do you mean by Q value of a nuclear reaction?
(b) Write down the expression for Q value in the case of α decay
(c) Two nuclei have mass numbers in the ratio 1 : 64. What is the ratio of their nuclear radii ?

a) Define half life period of a radioactive nucleus. Write down the relation connecting half life period and mean life
(b) Define 1 amu. Calculate its energy equivalent in MeV

a) T_½ is the time taken by the Radio Active element to decay its half ofthe initial value
T_½ = 0.693 τ
(b)
An atomic mass unit is defined as precisely 1/12 the mass of an atom of carbon-12
1 amu=1.6606×10⁻²⁷ kg
E = mc²
1 eV = 1.60218×10⁻¹⁹ J
E = 931.5 MeV

(a) Half-life is the time required for a Nuclei to reduce to half its initial value

(b) T_1/2= ln 2 / λ = 0.693 / λ

The energy required to separate all the nucleons inside a nucleus is called binding energy of the nucleus.
(a) Write an expression for binding energy in terms of mass defect.
(b) Draw the graph showing the variation of binding energy per nucleon as a function of mass number
(c) Which nucleus possess maximum binding energy per nucleon ?

(a) E_B = ΔM c² or
ΔM = u x 931 MeV or
E_B = (ZM_p+ (A - Z) M_n - M ) c²
(b)Graph (BE per Nucleon with Mass Number
(c) Iron (Fe)

Match the following :

	A	B
1	Nuclear fission	β-decay
2	Nuclear fusion	Hydrogen spectrum
3	Transition between atomic energy levels	Nuclei with low atomic numbers
4	Electron emission from nucleus	Generally possible for nuclei with high atomic number
		Photo electric emission

	A	B
1	Nuclear fission	Generally possible for nuclei with high atomic number
2	Nuclear fusion	Nuclei with low atomic numbers
3	Transition between atomic energy levels	Hydrogen spectrum
4	Electron emission from nucleus	β-decay

Spontaneous and continuous disintegration of a nucleus of a heavy element with the emission of certain types of radiation is known as radioactivity.
(a) The radioactive isotope ‘D’ decays according to the sequence shown in figure
If the mass number and atomic number of D₂ are 172 and 71 respectively, what are the
(i) Mass number, (ii) atomic number of D.
(b) State radioactive decay law.
(c) Write the relation connecting half-life and mean life of radioactive element.

(a)
(i) Mass number : 176
(ii) atomic number: 72

(b)
The number of nuclei undergoing the decay per unit time is proportional to the total number of nuclei in the sample
Or Equation (see figure)
(c) (see figure)