A radioactive substance has a half life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be

(1) 12.5%               

(2) 87.5%

(3) 8.5%                 

(4) 25.1%

Subtopic:  Radioactivity (OLD NCERT) |
 73%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

An element used for radioactive carbon dating for more than 5600 years is 

(1) C-14         

(2) U-234

(3) U-238       

(4) Po-94

Subtopic:  Radioactivity (OLD NCERT) |
 76%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

N atoms of a radioactive element emit n alpha particles per second. The half life of the element is

(1) nN sec                   

(2) Nn sec

(3) 0.693 Nn sec           

(4)  0.693 nN sec

Subtopic:  Radioactivity (OLD NCERT) |
 69%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

advertisementadvertisement

The radioactive nucleus N713 decays to C613 through the emission of 

(1) Neutron             

(2) Proton

(3) Electron             

(4) Positron

Subtopic:  Radioactivity (OLD NCERT) |
 61%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

The radioactive decay of uranium into thorium is expressed by the equation U92238Th90234+X where 'X' is

(1) An electron               

(2) A proton

(3) A deuteron                 

(4) An alpha particle

Subtopic:  Radioactivity (OLD NCERT) |
 88%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following would be emitted in the decay process 

(1) Proton             

(2) Neutron

(3) Electron           

(4) Photon

Subtopic:  Radioactivity (OLD NCERT) |
 76%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

advertisementadvertisement

The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be

(1) 93.75%                 

(2) 75%

(3) 25%                       

(4) 6.25%

Subtopic:  Radioactivity (OLD NCERT) |
 69%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

In the uranium radioactive series, the initial nucleus is U92238 and the final nucleus is Pb82206. When the uranium nucleus decays to lead, the number of  α-particles emitted will be 

(1) 1               

(2) 2

(3) 4               

(4) 8

Subtopic:  Types of Decay |
 85%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

Which of the following is a correct statement

(1) Beta rays are same as cathode rays

(2) Gamma rays are high energy neutrons

(3) Alpha particles are singly ionized helium atoms

(4) Protons and neutrons have exactly the same mass

Subtopic:  Types of Decay |
 53%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

advertisementadvertisement

The half life of I131 is 8 days. Given a sample of I131 at time t = 0, we can assert that 
(1) No nucleus will decay before t = 4 days

(2) No nucleus will decay before t = 8 days

(3) All nuclei will decay before t = 16 days

(4) A given nucleus may decay at any time after t = 0

Subtopic:  Radioactivity (OLD NCERT) |
 74%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch