Tag: chemistry

Questions Related to chemistry

All of the following are good laboratory practices except_________.

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. Wait for a hot object to cool before weighing it.

  2. Rinse a burette with the solution that will be used to fill the times

  3. Wear goggles at all times

  4. Return unused chemicals to the reagent bottles

  5. To dilute $H _2SO _4$, pour it into water slowly.

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Correct Option: A
Explanation:

We use different equipment to cool the object, before weighting it which save time.

Round 984 liters to 2 significant digits.

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. $1.00\times10^3$ liters

  2. 1000 liters

  3. 900 liters

  4. 980 liters

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Correct Option: D
Explanation:

$\text{980 have two non-zero digits ie. with significant figure is 2.}$

The result of the operation 2.5 X 1.25 should be which of the following on the basis of significant figures?

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. 3.125

  2. 3.13

  3. 3.1

  4. 31.25

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Correct Option: C
Explanation:
$2.5 \times 1.25 = 3.125$

The rule says: Answer to a multiplication or division should be rounded off to a same number of significant figures as possessed by the least precise term in the calculation.

Since $2.5$ has least numbers of significant figure i.e.two, thus, the result should have 2 significant figure i.e. $ 3.1$
option C is correct

Each side of a cube is measured to be $7.203$ m. What is the volume of the cube to appropriate significant figure?

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. $373.7m^3$

  2. $311.3 m^3$

  3. $211.3 m^3$

  4. $3737 m^3$

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Correct Option: A
Explanation:

Side of a cube$=7.203m$

                        $={(7.203)}^3$
                        $=373.714m^3$
$\therefore$  Volume of a cube $=373.7m^3$

In which of the following numbers, all zeros are significant?

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. 5.0005

  2. 0.0030

  3. 30.000

  4. 0.5200

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Correct Option: A
Explanation:

Any zeros between two significant digits are significant.

Non zero digits are always Significant.

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. True

  2. False

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Correct Option: A
Explanation:

Non zero digits are always significant it is a true statement.

Ex: $1234$ Total significant numbers are 4.

Calculate the following with due regard for significant figures:


 $\dfrac{1.53\times 0.9995}{1.592}$.

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. $0.961$

  2. $0.921$

  3. $0.123$

  4. $0.913$

Show answer
Correct Option: A
Explanation:

$1.53\times 0.9995=1.529=1.53$ .....By applying significant figure rule


$\cfrac { 1.53\times 0.9995 }{ 1.592 } =\cfrac { 1.53 }{ 1.592 } =0.961$

Hence, the correct option is $A$

If repeated measurements give values close to one another, the number is:

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. surely precise

  2. surely accurate

  3. surely precise and accurate

  4. all of these are correct

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Correct Option: A
Explanation:

Precision $=$ Individual value $-$ mean value

If the repeated measurement value is close to one another, the mean value will be close to the individual values. Therefore, their difference i.e. Precision is close to zero. Therefore, they are surely precise.
But the accuracy is the difference between the actual value & the mean value.
As we do not know the actual value, we cannot predict its accuracy.

The number of significant figures present in $4.50 \times 10^{3} $ is:

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. 2

  2. 3

  3. 4

  4. 5

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Correct Option: A
Explanation:
Number of significant figures present in $4.50 \times {10}^{3}$-
$4.50 \times {10}^{3} = 4500$
Thus, there are two significant figures.

The number of significant figures in 0.02300 is ?

chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

  1. 6

  2. 2

  3. 4

  4. 3

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Correct Option: C