Assertion :One atomic mass unit is defined as one twelfth of the mass of one carbon - 12 atom. Reason: Carbon - 12 isotope is the most abundant isotope of carbon and has been chosen as standard.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Assertion is correct but Reason is incorrect

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Both Assertion and Reason are incorrect

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
One atomic mass unit is defined as one-twelfth of the mass of one carbon - 12 atom because C-12 is chosen as the standard atom. This is because it has the equal number of protons and neutrons (6) and constitutes most of the matter.
The most abundant isotope of carbon is Carbon - 12.

Thus both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

Suggest Corrections

Similar questions

In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the option out of the choices given below in each question.

Assertion (A) One atomic mass unit is defined as one-twelfth of the mass of one carbon - 12 atom.

Reason (R) Carbon - 12 isotope is the most abundant isotope of carbon and has been chosen as the standard.

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

(b) Both A and R are true but R is not the correct explanation of A.

(d) Both A and R are false

Assertion: The mass of Chlorine is 35.5 u

Reason: For elements having isotopes, the average of mass of its isotopes is considered as the atomic mass of that element.

Assertion (A) Phenol forms 2, 4, 6-tribromophenol on treatment with $B r_{2}$ in carbon disulphide at 273K.
Reason (R) Bromine polarises in carbon disulphide.
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(e) Both assertion and reason are correct statements but reason is not correct explanation of assertion.

Q. Assertion : Two electrons of helium atom are placed in only one shell but three electrons of lithium need two shells.
Reason: A shell can have maximum

{2n}^{2}

electrons.

Q. Assertion: The compressibility factor for

H_{2}

and

H e

(1 + \frac{P b}{R T})

Reason: The compressibility factor for

H_{2}

and

H e

can be derived from Van der Waal's equation.

Join BYJU'S Learning Program