1. After the emission of one α - particle followed by one β - particle from the atom of 238X92 , the number of neutrons in the atom will be
1) 144 2) 143 3) 148 4) 146
2. In a radioactive decay an emitted electron comes from
1) Outermost orbit of the atom
2) Orbit having principal quantum number one
3) Nucleus of the atom
4) Inner orbit of the atom
4. The half life period of a radioactive element is 72 days. After 288 days one gram of the element will reduce to
5. The species 19Ne and 14C emit a positron and β - particle respectively the resulting species formed are respectively
1) 19Na and 14B 2) 19F and 14N
3) 19Na and 14N 4) 19Na and 14F
6. A radioactive element gets spilled over the floor of a room. Its half life period is 30 days. If the initial velocity is ten times the permissible value after how many days will it be safe to enter the room?
1) 100 2) 1000 3) 300 4) 10
7. Which of the following nuclear reactions will generate an isotope?
1) β - particle 2) neutron particle emission
3) positron emission 4) α - particle emission
8. Consider the following nuclear reactions
The number of neutrons in the element L is
1) 142 2) 144 3) 140 4) 146
Answers: 1-2; 2-3; 3-1; 4-3; 5-2; 6-1; 7-2; 8-2.
