Question

ASSERTION: Angstrom and AU are different units of length
REASON: Angstrom is a small unit of length while AU is a big unit of length
(A) both assertion and reason are correct and reason is the correct explanation for assertion
(B) both assertion and reason are correct but reason is not the correct explanation for assertion
(C) assertion is correct but reason is incorrect
(D) both assertion and reason are incorrect

Answer 1

Hint: The given quantities are angstrom and AU called an astronomical unit. We will come across through angstrom when we are doing calculations related to Bohr atomic theory and nucleus and atoms, while au we often see when we talk about astronomy and astrophysics.

Complete step by step answer:
One astronomical unit is defined as equivalent to 149,597,870,700 m. We know that metre is a unit of length and thus AU is also a unit of length. One au is equal to the distance between the earth and the sun.
Angstrom is a unit of length used to measure very small distances and mathematically it is equal to \[{{10}^{-10}}m\]. It is not a SI unit of length but a smaller unit.
So, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

So, the correct answer is “Option A”.

Note:
Both came out to be units of length, one very high in magnitude and one very small as compared to SI unit of length which is metre. There are 7 fundamental units to measure and which cannot be deduced from other quantities.