Assertion : Parallex method cannot be used for measuring distances of stars more than 100 light years away.

Reason : Because parallex angle reduces so much that it cannot be measured accurately.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

Assertion : Number of significant figures in 0.005 is one and that in 0.500 is three.

Reason : This is because zeros are not significant.

Assertion: Mass, length and time are fundamental physical quantities.

Reason: They are independent of each other.

Assertion : Density is a derived physical quantity.

Reason : Density cannot be derived from the fundamental physical quantities.

Assertion: Nowadays a standard metre is defined in terms of the wavelength of light.

Reason: Light has no relation with length.

Assertion: Surface tension and surface energy have the same dimensions.

Reason: Because both have the same S.I. unit

Assertion : In $y=A\sin (\omega t-kx),$ $(\omega t-kx)$ is dimensionless.

Reason : Because dimension of $\omega =\left[M^0{L}^{0}T\right].$

Assertion : Radian is the unit of plane angle.

Reason : One radian is the angle subtended at the centre of a circle by an arc equal in length to the radius of the circle.

Choose any one of the following four responses :

(1) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(2) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(3) If assertion is true but reason is false.

(4) If the assertion and reason both are false

Assertion : A.U. is much bigger than Å.

Reason : A.U. stands for astronomical unit and Å stands from Angstrom.