Tag: significant figures and rounding of digits

Questions Related to significant figures and rounding of digits

What is the value of $\sqrt { 79.62 } $ ?

  1. 8.923

  2. 8.9230

  3. 8.92300

  4. 8.9326


Correct Option: A
Explanation:

$\sqrt{79.62}=8.92300397$
Since 79.62 has 4 significant digits, so we express our answer in 4 significant digits.
$\Rightarrow \sqrt{79.62}=8.923 \rightarrow$ 4 significant figures.

The volume of a sphere is $ 1.76\;{cm }^{ 3 }$. The volume of 25 such spheres according to the idea of significant figures in ${cm}^{ 3 }$ is 

  1. 44.00

  2. 44.0

  3. 44

  4. 4.4


Correct Option: B
Explanation:

Volume of 1 sphere $=1.76 cm^{3}$
Volume of 25 spheres $=25\times 1.76$
                                      $=44 {cm}^{3}$
                                      $=44.0 {cm}^{3}$
                                 (Since volume is reported in 3 significant figure)

According to theory of significant figures $\left( 2.0 \right) ^{ 10 }$ is :

  1. 1024

  2. $1.024\times { 10 }^{ 10 }$

  3. $1.0\times { 10 }^{ 3 }$

  4. 1000


Correct Option: C
Explanation:

$\left ( 2.0 \right )^{10}=1024$
But since 2.0 contains 2 significant figure.
So, $1024=1.0\times 10^{3}$

A body of mass $m =3.513\ kg$ is moving along the x-axis with a speed of $5.00{ ms }^{ -1 }$. The magnitude of its momentum is recorded as :

  1. $17.56\ kg{ ms }^{ -1 }$

  2. $17.57\ kg{ ms }^{ -1 }$

  3. $17.6\ kg{ ms }^{ -1 }$

  4. $17.565\ kg{ ms }^{ -1 }$


Correct Option: C
Explanation:

Momentum$=mv=3.513\times 5.00=17.565\approx 17.57$
$\approx 17.6 kg m/s$
(Since 5.00 contains  least no. of significant figures i.e. 3)

A student measure the thickness of an object by three different instruments and gets the result as 0.5 cm, 0.50 cm, 0.500 cm. State the one which is more accurate. 

  1. $0.5$ cm

  2. $0.50$ cm

  3. $0.500$ cm

  4. All the measurements are equally accurate.


Correct Option: C
Explanation:

Since, the measurement $0.500 \ cm$ gives the reading up to 3 decimel, thus $0.500 \ cm$ is the most accurate measurement among the given three measurements.

In the number 2.4560, there are 5 significant digits. Which one is the least significant digit?

  1. 2

  2. 4

  3. 0

  4. 6


Correct Option: C
Explanation:

The least significant digit is the lowest digit in a number, located at the far right of a string.


Here 0 is the rightmost side of this number so this is least significant digit.


Option C is the correct answer

Significant figures in 0.00051 are

  1. 5

  2. 3

  3. 2

  4. 4


Correct Option: C
Explanation:
In the given number  $0.00051$, the zeros to the left of the non-zero digit are not considered as significant figures.
Thus, the given number has only 2 significant figures.

Which of the following numbers has least number of significant figures?

  1. $0.80760$

  2. $0.80200$

  3. $0.08076$

  4. $80.267$


Correct Option: C
Explanation:

If there is a decimal point, the rightmost digit is the last or least significant figure. So 0.08076 is the least significant figure

The number of significant figures in 10.02 is :

  1. 1

  2. 2

  3. 3

  4. 4


Correct Option: D
Explanation:

Since, all the non zero digits and zeros between the non-zero digits are considered as significant figures. Thus the number $10.02$ has $4$ significant figures.

The number of significant figures of $0.0632 m$ is :

  1. $5$

  2. $4$

  3. $3$

  4. $2$


Correct Option: C
Explanation:

Zeros to the left of the non-zero digits are considered as significant figures. All non-zero digits are also considered as significant figures. Thus the number  $0.0632$ has $3$ significant figures.