`K`-capture
a. Refers to capture by other nucleus of an electron from `K`-shell
b. Results in decrease in `Z`
c. Is of the type
`._(56)Ba^(133) + ._(-1)e^(0) rarr ._(55)Cs^(133) _ gamma`-rays d. All of these

Following reactions are known as inverse beta decay p+vecvrarrn+e^(+) n+vrarrp+e^(-) These reactions have extremely low probabilities. Because of this, neutrinos and antineutrinos are able to pass through vast amount of matter without any interaction. In an experiment to detect neutrinos, large number of neutrinos coming out from beta decays of a radioactive material were made to pass through a tank of water, containing a cadmium compound in solution, which provided the protons to interact with antineutrinos, which provided the protons to interact with antineutrinos. Immediately after a proton absorbed a neutrino to yield a positron and a neutron, the positron encountered an electron and both got annihilated. the gamma ray detectors surrounding the tanks responded to the resulting photons. This confirmed that the above reaction has taken place. (a) How many gamma ray photons are produced when a electron annihilates with a positron? What is energy of each photon? Take the mass of an electron to be 0.00055 u. (b) The neutron produced in the above reaction was captured by .^(112)Cd to form .^(113)Cd . The atomic masses of these two isotopes of cadmium are are 111.9028u and 112.9044u respectively. mass of a neutron is 1.0087u. find the Q value of this reaction. Assume half of this energy is excitation energ of .^(113)Cd . if the nucleus de-excites by emitting a gamma ray photon find its wavelenght.

In an electron capture process, a nucleus captures an electron from K shell of the atom. The electron is having a binding energy of B_(0) . Followed by this capture of electron, several photons are emitted due to electronic transitions. What will be Sum of energy of all such photons emitted?

The reducing effect of the nuclear charge by the inner electrons for on outer electron is termed aas shielding (or screening). As a result of shielding, the outer electrons in an atom always experience less nnuclear charge than the actual nuclear charge Z. The effective nuclear charge (Z^(**)) as experienced by an electron is then obtained by subtracting the total shielding contributions from alll the other electrons (i.e., except the one under consideration) from the actual nuclear charge. Z^(**)=Z-sigma Where sigma =sum of the shielding contributions. The rules for estimating contributions to sigma are as follows (Slater's rule) Contribution to shielding by each electron is : |{:("Electron","All Higher","Same","Group","Group"le),("Grpoup","Group","Group",n-1,n-2),(1s," "0,0.30,-,-),((ns,sp)," "0,0.35,0.85,1.00),((nd)or(nf)," "0,0.35,1.00,1.00):}| According to Slater's treatment, the energy of an electron in nth shell of an atom having atomic number Z is given by the empirical equation E=-13.6((Z^(**))/(n))^(2)eV Z^(**) = effective nuclear charge Among the following, which electron of Fe atom experience minimum attraction from nucleus? (Atomic number of Fe = 26)

The reducing effect of the nuclear charge by the inner electrons for on outer electron is termed aas shielding (or screening). As a result of shielding, the outer electrons in an atom always experience less nnuclear charge than the actual nuclear charge Z. The effective nuclear charge (Z^(**)) as experienced by an electron is then obtained by subtracting the total shielding contributions from alll the other electrons (i.e., except the one under consideration) from the actual nuclear charge. Z^(**)=Z-sigma Where sigma =sum of the shielding contributions. The rules for estimating contributions to sigma are as follows (Slater's rule) Contribution to shielding by each electron is : |{:("Electron","All Higher","Same","Group","Group"le),("Grpoup","Group","Group",n-1,n-2),(1s," "0,0.30,-,-),((ns,sp)," "0,0.35,0.85,1.00),((nd)or(nf)," "0,0.35,1.00,1.00):}| According to Slater's treatment, the energy of an electron in nth shell of an atom having atomic number Z is given by the empirical equation E=-13.6((Z^(**))/(n))^(2)eV Z^(**) = effective nuclear charge The size of isoelectronic species -F^(-),Na^(+) and Mg^(2+) is effected by:

The reducing effect of the nuclear charge by the inner electrons for on outer electron is termed aas shielding (or screening). As a result of shielding, the outer electrons in an atom always experience less nnuclear charge than the actual nuclear charge Z. The effective nuclear charge (Z^(**)) as experienced by an electron is then obtained by subtracting the total shielding contributions from alll the other electrons (i.e., except the one under consideration) from the actual nuclear charge. Z^(**)=Z-sigma Where sigma =sum of the shielding contributions. The rules for estimating contributions to sigma are as follows (Slater's rule) Contribution to shielding by each electron is : |{:("Electron","All Higher","Same","Group","Group"le),("Grpoup","Group","Group",n-1,n-2),(1s," "0,0.30,-,-),((ns,sp)," "0,0.35,0.85,1.00),((nd)or(nf)," "0,0.35,1.00,1.00):}| According to Slater's treatment, the energy of an electron in nth shell of an atom having atomic number Z is given by the empirical equation E=-13.6((Z^(**))/(n))^(2)eV Z^(**) = effective nuclear charge Atomic radii of the noble gases are larger than the precedent elements of the same periods because:

The reducing effect of the nuclear charge by the inner electrons for on outer electron is termed aas shielding (or screening). As a result of shielding, the outer electrons in an atom always experience less nnuclear charge than the actual nuclear charge Z. The effective nuclear charge (Z^(**)) as experienced by an electron is then obtained by subtracting the total shielding contributions from alll the other electrons (i.e., except the one under consideration) from the actual nuclear charge. Z^(**)=Z-sigma Where sigma =sum of the shielding contributions. The rules for estimating contributions to sigma are as follows (Slater's rule) Contribution to shielding by each electron is : |{:("Electron","All Higher","Same","Group","Group"le),("Grpoup","Group","Group",n-1,n-2),(1s," "0,0.30,-,-),((ns,sp)," "0,0.35,0.85,1.00),((nd)or(nf)," "0,0.35,1.00,1.00):}| According to Slater's treatment, the energy of an electron in nth shell of an atom having atomic number Z is given by the empirical equation E=-13.6((Z^(**))/(n))^(2)eV Z^(**) = effective nuclear charge Which of the following statements is correct?

Fill in the blanks in the following statements : (a) The number of protons in the nucleus of an atom is called its ……… (b) The total number of protons and neutrons in the nucleus of an atoms is called its ……… (c) An atom has atomic mass number 23 and atomic number 11. The atom has ....... electrons. (d) An atom of an element has 11 protons, 11 electrons and 12 neutrons. The atomic mass of the atom is ........ (e) If the nucleus of an atom has atomic number 17, mass number 37 and there are 17 electrons outside the nucleus, the number of neutrons in it is ........ (f) Almost all the mass of an atom is concentrated in a small region of space called the ........ (g) Cathode rays are a beam of fast moving ........ (h) The anode rays obtained from hydrogen gas consist of particles called ........ (i) The maximum number of electrons that can be accommodated in L shell are ........ (j) The maximum number of electrons that can go into the M shell is ....... (k) The subatomic particle not present in a hydrogen atom is ......... (l) The electron has .......... charge, the proton has ......... charge, and the neutron has .......... charge.

Unstable nuclei attain stability through disintegration. The nuclear stability is related to neutron proton ratio (n//p) . For stable nuclei n//p ratio lies close to unity for elements with low atmoic numbers (20 or less) but it is more than 1 for nuclei having higher atomic numbers. Nuclei having n//p ratio either very high or low undergo nuclear transformation. When n//p ratio is higher than required for stability, the nuclei have the tendency to emit beta -rays. while when n//p ratio is lower than required for stability, the nuclei either emits alpha -particles or a positron or capture K -electron. For reaction ._(92)M^(238) rarr ._(y)N^(x) + 2 ._(2)He^(4), ._(y)N^(x) rarr ._(B)L^(A) + 2 ._(-1)e^(0) The number of neutrons in the element L is