Assertion : ‘Light year’ and ‘Wavelength’ both measure distance.

Reason : Both have dimensions of time.

Assertion : Light year and year, both measure time.

Reason : Because light year is the time that light takes to reach the earth from the sun.

Assertion : Force cannot be added to pressure.

Reason : Because their dimensions are different.

Assertion : Linear mass density has the dimensions of $\left[M^1{L}^{-1}{T}^o\right]$.

Reason : Because density is always mass per unit volume.

Assertion : Rate of flow of a liquid is defined as volume of liquid flowing per second.

Reason : The dimensions of rate of flow are $\left[M^0{L}^1{T}^{-1}\right]$.

Assertion: Units of Rydberg constant R are m^-1

Reason: It follows from Bohr’s formula $\overline{v}=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$, where the symbols have their usual meaning.

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.

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.