Tag: chemistry

Questions Related to chemistry

Which tool can be used to make precise measurements of varying volumes?

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  1. Beaker

  2. Graduated cylinder

  3. Volumetric flask

  4. Test tube

Show answer
Correct Option: A
Explanation:

Beaker can be used to make precise measurements of varying volumes. A beakes is basically a broad cylindrical container with a flat bottom. It has a small spout to aid pouring. It also has some graduations for measurement of liquid.

What will happen if glass rod is made from reacting compound :

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  1. It may cause certain accidents in the laboratory when exposed to certain chemicals

  2. It will interacts with the chemicals in the solution

  3. it will be corrosive to the atmosphere

  4. All of these

Show answer
Correct Option: D
Explanation:

If glass rod is made from reacting compound it will interact with the chemicals in the solution and contaminate the solution. It may cause certain accidents in the laboratory when exposed to certain chemicals. Also, it could be corrosive to atmosphere due to its reactive nature. 

The functions of cork stopper are :

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  1. restrics the vapour of the container to go out

  2. helps in condensation

  3. restricts moisture to come in contact with the solution

  4. both A and B

Show answer
Correct Option: A,B,C
Explanation:

Cork stopper is often used when a reaction is taking place in the flask or test tube and the by product or result of the reaction is desired to be collected. Its basic function is to plug.

It is widely used in fractional distillation. It restrics the vapour of the container from going out, helps in condensation and also restricts moisture to come in contact with the solution.

Glass rod are generally used to stir liquid chemicals because :

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  1. it provides controlled agitation to the reaction

  2. it does not react with chemicals in the solution

  3. it has a rounded ends to support proper stirring

  4. all of these

Show answer
Correct Option: D
Explanation:

A glass rod, stirring rod or stir rod is a piece of laboratory equipment used to mix chemicals and liquids for laboratory purposes. They are usually made of solid glass, about the thickness and slightly longer than a drinking straw, with rounded ends.

Since glass is a non-crystalline amorphous solid and is silica-based it does not react with chemicals in solution. 

Also, we can control the agitation as we ourselves stir the solution using glass rod.  

A glass rod is also called :

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  1. stirring rod

  2. stir rod

  3. both A and B

  4. none of these

Show answer
Correct Option: C
Explanation:

A glass rod, stirring rod or stir rod is a piece of laboratory equipment used to mix chemicals and liquids for laboratory purposes. They are usually made of solid glass, about the thickness and slightly longer than a drinking straw, with rounded ends.

What is the first thing a chemistry student do if flames start coming out of the bottom of a Bunsen Burner?

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  1. Adjust the collar.

  2. Adjust the flow rate of the gas.

  3. Notify the instructor.

  4. Find the fire extinguisher.

  5. Turn off the gas supply.

Show answer
Correct Option: A
Explanation:

When flames start coming out of the bottom of the bunsen. One should adjust the collar of the burner so that it is sealed and flames stop coming out.

Which selection would be used to purify solid $NaCl$ from an aqueous solution of $NaCl$?

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  1. Crucible

  2. Evaporating

  3. Tongs

  4. Erlenmeyer flask

  5. Mortar and pestle

Show answer
Correct Option: B
Explanation:
Evaporating dish $\rightarrow$
It is used to evaporate excess solvents (most commonly water) to produce a concentrated solution or a solid precipitate of the dissolved substance. 
Hence it can be used to purify solid $NaCl$ from an aqueous solution of $NaCl$.
Hence the required answer is (B) Evaporating dish.

Cork stopper are used as _____ in the chemistry laboratory.

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  1. plug

  2. inlets

  3. outlets

  4. none of them

Show answer
Correct Option: A
Explanation:

Cork stopper is often used when a reaction is taking place in the flask or test tube and the by product or result of the reaction is desired to be collected. Its basic function is to plug. 

What are the uses of glass tube?

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  1. Laboratory glassware

  2. Lighting application

  3. Solar thermal system and pharmaceutical packaging

  4. All of these

Show answer
Correct Option: D
Explanation:

Glass tubes or glass tubing are hollow pieces of various glass types (like borosilicate, flint, aluminosilicate, soda lime, lead or quartz glass) with a large variety of applications which are laboratory glassware, lighting applications, solar thermal systems and pharmaceutical packaging.

Fill in the blanks by choosing an appropriate option.
When sugar is dissolved in water, it undergoes a (i) change but if sugar is heated in a test tube over the Bunsen burner flame, it first melts, turns brown and finally turns (ii). The new substance formed is __(iii)_ and the change is a _(iv)_ change.

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  1. (i) - Physical reversible, (ii) - Black, (iii) - Charcoal, (iv) - Chemical irreversible

  2. (i) - Physical irreversible, (ii) - Black, (iii) - Coal, (iv) - Chemical irreversible

  3. (i) - Physical irreversible, (ii) - Red, (iii) - Charcoal, (iv) - Chemical reversible

  4. (i) - Physical reversible, (ii) - Red, (iii) - Coal, (iv) - Chemical reversible

Show answer
Correct Option: A
Explanation:

Dissolving sugar in water is a physical, reversible change. When sugar is heated, it decomposes into carbon and water (chemical reversible change).

$C _{12}H _{22}O _{11} \rightarrow       C    +    H _2O$
                                                        Carbon        (Steam)