Tag: chemistry

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Questions Related to chemistry

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

All of the following are good laboratory practices except_________.

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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

  1. 3.125

  2. 3.13

  3. 3.1

  4. 31.25
Reveal answer Fill a bubble to check yourself
C Correct answer
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
Multiple choice chemistry measurement and data processing and analysis uncertainties and errors, graphical techniques uncertainty in measurement measurement of properties

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

  1. $373.7m^3$
  2. $311.3 m^3$
  3. $211.3 m^3$
  4. $3737 m^3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Side of a cube$=7.203m$

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

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

Calculate the following with due regard for significant figures:


 $\dfrac{1.53\times 0.9995}{1.592}$.

  1. $0.961$
  2. $0.921$
  3. $0.123$
  4. $0.913$
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $A$

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

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

  1. surely precise

  2. surely accurate

  3. surely precise and accurate

  4. all of these are correct
Reveal answer Fill a bubble to check yourself
A Correct answer
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.