The angle of \(1'\) (minute of an arc) in radian is nearly equal to:
1. \(2.91 \times 10^{-4}~\text{rad} \)
2. \(4.85 \times 10^{-4}~\text{rad} \)
3. \(4.80 \times 10^{-6} ~\text{rad} \)
4. \(1.75 \times 10^{-2}~\text{rad} \)

Time intervals measured by a clock give the following readings: 
\(1.25~\text{s},~1.24~\text{s}, ~1.27~\text{s},~1.21~\text{s},~1.28~\text{s}.\) 
What is the percentage relative error of the observations? 
1. \(2\)%
2. \(4\)%
3. \(16\)%
4. \(1.6\)%

19. We have different units for the same physical quantity,

(a) To have the different dimensions

(b) To have the same value in the different units

(c) To have a wide range of the measurements

(d) None of the above

This objective question is based on NCERT Exemplar subjective Question.

The radius of the atom is of the order of 1 $\stackrel{\mathrm{o}}{\mathrm{A}}$ and the radius of a nucleus is of the order of fermi. How many magnitudes higher is the volume of an atom as compared to the volume of the nucleus?

$\left(1\right)<mspace\; width="1em"></mspace>{10}^{13}$
$\left(2\right)<mspace\; width="1em"></mspace>{10}^{14}$
$\left(3\right)<mspace\; width="1em"></mspace>{10}^{15}$
$\left(4\right)<mspace\; width="1em"></mspace>{10}^{16}$

This objective question is based on NCERT Exemplar subjective Question.

The device used for measuring the mass of atoms and molecules:

(1) Odometer

(2) Spectrometer

(3) Seismograph

(4) Spring Balance

This objective question is based on NCERT Exemplar subjective question.

The unified atomic mass unit in kg is equal to:

$\left(1\right)<mspace\; width="1em"></mspace>1.67\times {10}^{+27}$
$\left(2\right)<mspace\; width="1em"></mspace>3.2\times {10}^{-27}$
$\left(3\right)<mspace\; width="1em"></mspace>1.67\times {10}^{-27}$
$\left(4\right)<mspace\; width="1em"></mspace>9.1\times {10}^{-27}$

This objective question is based on NCERT Exemplar subjective Question.

23. A function f($\mathrm{\theta }$) is defined as $\mathrm{f}\left(\mathrm{\theta }\right)=1-\mathrm{\theta }+\frac{{\mathrm{\theta }}^2}{2!}-\frac{{\mathrm{\theta }}^3}{3!}+\frac{{\mathrm{\theta }}^4}{4!}+<mspace\; width="1em"></mspace>...$
f($\mathrm{\theta }$) is a dimensionless quantity because:

(a) $\mathrm{\theta }$ is dimensionless.

(b) Combination of different powers of $\mathrm{\theta }$ is dimensionless.

(c) It has no relation with $\mathrm{\theta }$.

(d) None of the above

(1) (a, c)

(2) (b, c)

(3) (a, b)

(4) (d) only

This objective question is based on NCERT Exemplar subjective Question.

24. Length, mass, and time are chosen as base quantities in mechanics because

(a) these are special quantities.

(b) these are independent quantities.

(c) these are independent of other quantities but depend on each other.

(d) these are only the measurable quantities.

This objective question is based on NCERT Exemplar subjective Question.

25. The earth-moon distance is about 60 earth radius. What will be the diameter of the earth (approximately in degrees) as seen from the moon?

(a) 2$°$

(b) 1$°$

(c) 3$°$

(d) 4$°$

This objective question is based on NCERT Exemplar subjective Question.

Which of the following time measuring devices is most precise:

(a) A wall clock
(b) A stopwatch
(c) A digital watch
(d) An atomic clock

This objective question is based on NCERT Exemplar subjective Question