All Courses
Explore Courses UPSC Exam UPSC Test Series Free Notes EduRev Infinity Get the App Login Join for Free
Sign in Open App
Class 12 Exam  >  Class 12 Questions  >  Directions : In the following questions, A st... Start Learning for Free
SaveJoin the Discussion on the App
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.


Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.


Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.

  • a)
    Both A and R are true and R is the correct explanation of A

  • b)
    A is true but R is false

  • c)
    Both A and R are true but R is NOT the correct explanation of A 

  • d)
    A is false and R is true

Correct answer is option 'B'. Can you explain this answer?
FREE This question is part of
Download PDF Attempt Test
Download PDF Attempt this Test
Most Upvoted Answer
Directions : In the following questions, A statement of Assertion (A) ...
Two atoms of different elements having the same mass number but different atomic numbers are called isobars. The assertion is true. Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus. The reason is also false.  The correct Reason (R) should be: Mass number is the total number of protons and neutrons present in a nucleus.



Free Test
FREE
Start Free Test
Start Free Test
Community Answer
Directions : In the following questions, A statement of Assertion (A) ...
Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.

Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.

The correct answer is option 'B' - A is true but R is false.

Explanation:
Isobars:
- Isobars are atoms of different elements that have the same mass number (sum of protons and neutrons), but different atomic numbers (number of protons).
- Isobars have similar masses but different chemical properties due to the difference in the number of protons, which determines the element's identity.

Atomic Number:
- The atomic number of an element is the number of protons present in the nucleus of an atom.
- It is denoted by 'Z' and defines the element's identity as each element has a unique atomic number.
- In a neutral atom, the atomic number also represents the number of electrons present.

Mass Number:
- The mass number of an atom is the sum of the number of protons and neutrons present in the nucleus.
- It is denoted by 'A' and represents the atomic mass or weight of the atom.

Explanation of Assertion (A):
- The statement in Assertion (A) is correct. Two atoms of different elements having the same mass number but different atomic numbers are called isobars.
- Isobars have the same total number of protons and neutrons (mass number) but different numbers of protons (atomic number), leading to different elements.

Explanation of Reason (R):
- The statement in Reason (R) is incorrect. The atomic number is the number of protons present in the nucleus of an atom, not the total number of protons and neutrons.
- The correct definition for the total number of protons and neutrons is the mass number, not the atomic number.

Conclusion:
- While Assertion (A) is true, Reason (R) is false as it provides an incorrect definition of atomic number.
- Therefore, the correct answer is option 'B' - A is true but R is false.
< Previous Question Next Question >
Explore Courses for Class 12 exam

Similar Class 12 Doubts

Directions : Read the passage given below and answer the following questions :Scuba apparatus includes a tank of compressed air toted by the diver on his or her back, a hose for carrying air to a mouthpiece, a face mask that covers the eyes and nose, regulators that control air flow, and gauges that indicate depth and how much air remains in the tank.A diver who stays down too long, swims too deep, or comes up too fast can end up with a condition called “the bends.” In this case, bubbles of gas in the blood can cause intense pain, even death.In these following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : Scuba divers may face a medical condition called ‘bends’.Reason : ‘Bends’ can be explained with the help of Henry’s law as it links the partial pressure of gas to that of its mole fraction.

Directions : Read the passage given below and answer the following questions :Scuba apparatus includes a tank of compressed air toted by the diver on his or her back, a hose for carrying air to a mouthpiece, a face mask that covers the eyes and nose, regulators that control air flow, and gauges that indicate depth and how much air remains in the tank.A diver who stays down too long, swims too deep, or comes up too fast can end up with a condition called “the bends.” In this case, bubbles of gas in the blood can cause intense pain, even death.In these following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : Bends is caused due to formation of nitrogen bubbles in the blood of scuba divers which blocks the capillaries.Reason : Underwater high pressure increases solubility of gases in blood, while as pressure gradually decreases moving towards the surface, gases are released and nitrogen bubbles are formed in blood.

Directions : Read the passage given below and answer the following questions :Scuba apparatus includes a tank of compressed air toted by the diver on his or her back, a hose for carrying air to a mouthpiece, a face mask that covers the eyes and nose, regulators that control air flow, and gauges that indicate depth and how much air remains in the tank.A diver who stays down too long, swims too deep, or comes up too fast can end up with a condition called “the bends.” In this case, bubbles of gas in the blood can cause intense pain, even death.In these following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.Assertion : Soft drinks and soda water bottles are sealed under high pressure.Reason : High pressure maintains the taste and texture of the soft drinks.

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer?
Question Description
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer?.
Solutions for Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? in English & in Hindi are available as part of our courses for Class 12. Download more important topics, notes, lectures and mock test series for Class 12 Exam by signing up for free.
Here you can find the meaning of Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer?, a detailed solution for Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? has been provided alongside types of Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.Assertion (A): Two atoms of different elements having the same mass number but different atomic numbers are called isobars.Reason (R): Atomic number is the number of protons present and atomic number is the total number of protons and neutrons present in a nucleus.a)Both A and R are true and R is the correct explanation of Ab)A is true but R is falsec)Both A and R are true but R is NOT the correct explanation of Ad)A is false and R is trueCorrect answer is option 'B'. Can you explain this answer? tests, examples and also practice Class 12 tests.
Explore Courses for Class 12 exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Get App
© EduRev
Education Revolution
Follow Us
Signup to see your scores go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup