The following is/are not a unit of time:

(a)	second
(b)	parsec
(c)	year
(d)	light year

Choose the correct option:

1.	(a, c, d)
2.	(a, c)
3.	(b, d)
4.	(b, c)

29. During a total solar eclipse-the moon almost entirely covers the sphere of the sun. The relation between the distances and sizes of the sun and moon is:

$\left(1\right)<mspace\; width="1em"></mspace>\frac{{\mathrm{R}}_{\mathrm{s}}}{{\mathrm{R}}_{\mathrm{m}}}=\frac{{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{R}}_{\mathrm{me}}}$
$\left(2\right)<mspace\; width="1em"></mspace>\frac{{\mathrm{R}}_{\mathrm{s}}}{{\mathrm{R}}_{\mathrm{m}}}={\left(\frac{{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{R}}_{\mathrm{me}}}\right)}^2$
$\left(3\right)<mspace\; width="1em"></mspace>\frac{{\mathrm{R}}_{\mathrm{s}}}{{\mathrm{R}}_{\mathrm{m}}}=\sqrt{\frac{{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{R}}_{\mathrm{me}}}}$
$\left(4\right)<mspace\; width="1em"></mspace>\frac{{\mathrm{R}}_{\mathrm{m}}}{{\mathrm{R}}_{\mathrm{s}}}=\frac{{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{R}}_{\mathrm{me}}}$

This objective question is based on NCERT Exemplar subjective Question.

Which of the following ratios, express pressure?

Choose the correct option:

If Planck's constant \((h)\) and speed of light in a vacuum \((c)\) are taken as two fundamental quantities, which one of the following can, in addition, be taken to express length, mass, and time in terms of the three chosen fundamental quantities?

Photon is a quantum of radiation with energy E = h$\mathrm{\nu }$, where $\mathrm{\nu }$ is the frequency
and h is Planck's constant. The dimensions of h are the same as that of the following quantities.

(a) linear impulse

(b) angular impulse

(c) linear momentum

(d) angular momentum

Choose the correct option:

1. (a, d)

2. (b, d)

3. (c, d)

4. (a, b)

IF \(P, Q\) and \(R\) are physical quantities, having different dimensions, which of the following combination/s can never be a meaningful quantity?

(a) \((P – Q)/R\)
(b) \(PQ – R\)
(c) \(PQ /R\)
(d) \((PR – Q^2)/R\)
(e) \((R + Q)/P\)
 
Choose the correct option:
1. (a), (e)
2. (a), (d), (e)
3. (a), (c), (d)
4. (b), (d)

On the basis of dimensions, decide which of the following relations for the displacement of a particle undergoing simple harmonic motion is/are not correct.

(Symbols have their usual meanings.)
Choose the correct option:

Young's modulus of steel is \(1.9 \times 10^{11} ~\text{N/m}^2\). When expressed in CGS units of \(\text{dyne/cm}^2\), it will be equal to: \((1 \mathrm{~N}=10^5 \text { dyne, } 1~ \text{m}^2=10^4 ~\text{cm}^2)\)
1. \( 1.9 \times 10^{10} \)
2. \( 1.9 \times 10^{11} \)
3. \( 1.9 \times 10^{12} \)
4. \( 1.9 \times 10^9\)

The mean length of an object is \(5~\text{cm}.\) Which of the following measurements is the most accurate?