Tag: chemistry

Questions Related to chemistry

State whether true or false :

Ropes made by rayon are used in cranes and elevators.

chemistry substances in daily use polyester and acrylic rayon and nylon synthetic fibres

  1. True

  2. False

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Correct Option: B
Explanation:
Rayon is a manufactured fiber made from regenerated cellulose fiber. 

It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound. 

Because rayon is manufactured from naturally occurring polymers, it is considered a semisynthetic fiber and the strength is not enough that can withstand high stress to be used in cranes and elevators like metal ropes.

Therefore, option B is correct

Ropes made of _______ are used in cranes and lifts.

chemistry substances in daily use polyester and acrylic rayon and nylon synthetic fibres

  1. rayon

  2. nylon

  3. acrylic

  4. spandex

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Correct Option: B
Explanation:

Nylon ropes are used in cranes and lifts because of high tensile strength and elasticity of nylon.


Nylon is the strongest of all ropes in common use. It is used for absorbing shock loads, such as when lifting or towing because it has the ability to return to it's original length after being stretched. 

It also has good abrasion resistance and can last several times longer than natural fibres.

Therefore, option B is correct.

Nylon is obtained from :

chemistry substances in daily use polyester and acrylic rayon and nylon synthetic fibres

  1. coal

  2. air

  3. water

  4. all of the above

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Correct Option: D
Explanation:

Nylon was the first fully synthetic fibre obtained from coal, water and air.

Name the plastic whose sheets are used for packing liquids.

chemistry substances in daily use polyester and acrylic rayon and nylon synthetic fibres

  1. Polythene

  2. Polycot

  3. Polywool

  4. Polyester

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Correct Option: A
Explanation:
In order to pack the liquids, Polyethylene terepthalate is used.

It is an important substance that can store the liquid without leakage.

It is a polymer of ethylene terepthalate and is quite durable in carrying the stuff from one place to another.

Strength and durability are the two important factors that make it an important choice.

Hence, the correct option is $\text{A}$

Which of the following does NOT form an acidic salt?

salts salts and their classification acids, bases and salts chemistry

  1. Phosphoric acid

  2. Carbonic acid

  3. Hydrochloric acid

  4. Sulphuric

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Correct Option: B

Lime water + sulphuric acid $\rightarrow$

salts salts and their classification acids, bases and salts chemistry

  1. Heat + Calcium sulphate

  2. Water + Heat

  3. Calcium sulphate + Water + Heat

  4. None of the above

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Correct Option: C
Explanation:

Lime water/calcium hydroxide $Ca(OH) _2$ is a strong base and sulphuric acid $H _2SO _4$ is a strong acid as they undergo complete dissociation in solution.

When acid and base react with each other, the base neutralizes the acid, leading to the formation of salt and water.
This reaction is known as neutralization reaction and it is exothermic in nature (since heat is released due to formation of new bonds in the reaction).
Thus, more stronger the acid and the base, more amount of heat is released.
$Ca(OH) _2 + H _2SO _4 \rightarrow CaSO _4+2H _2O + Heat$.
Hence, the correct answer is option (C).

Which technique produces a compound which is not soluble in water?

salts salts and their classification acids, bases and salts chemistry

  1. Conductivity

  2. Calorimetry

  3. Precipitation

  4. Spectrophotometry

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Correct Option: C
Explanation:

A reaction occurs when you mix two aqueous solutions. This is when you will find out whether a precipitate will form or not. A precipitate forms if the product of the reaction is insoluble in water.

Precipitation occurs when cations and anions in the aqueous solution combine to form an insoluble ionic solid called a precipitate.
Conductivity is the property to conduct electricity, calorimetry is the process of measuring the heat of chemical reactions and spectrophotometry is the measurement of reflection or transmission properties of the material as a function of wavelength.
Since precipitation produces a compound which is not soluble in water, the correct answer is the option (C).

When the aqueous solution of silver nitrate and sodium chloride are mixed, a________ precipitate is immediately formed.

salts salts and their classification acids, bases and salts chemistry

  1. yellow

  2. white

  3. red

  4. black

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Correct Option: B
Explanation:

When silver nitrate $(AgNO _3)$ reacts with sodium chloride $(NaCl)$ a white precipitate of silver chloride $(AgCl)$ is formed which is highly insoluble in water, along with formation of sodium nitrate $(NaNO _3)$.

Since $(AgCl)$ is insoluble in water it will precipitate out and $(NaNO _3)$ is soluble in water so it will remain dissolved in the mixture. This reaction is an example of double displacement reaction and it occurs as follows:-
$AgNO _3\ +\ NaCl \rightarrow AgCl\ +\ NaNO _3 $
Hence, the correct answer is the option (B).

${ H } _{ 3 }{ PO } _{ 4 }$ is a tribasic acid and one of its salt is $Na{ H } _{ 2 }{ PO } _{ 4 }$. What volume of 1M NaOH solution should be added to 12g $Na{ H } _{ 2 }{ PO } _{ 4 }$ to convert it into $Na _{ 3 }{ PO } _{ 4 }$? (at.wt of P=31)

salts salts and their classification acids, bases and salts chemistry

  1. 100 mL

  2. 200 mL

  3. 80 mL

  4. 300 mL

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Correct Option: B
Explanation:

$NaH _2PO _4$ + $ 2 NaOH $ $ \rightarrow Na _3PO _4 + H _2O $

From the above reaction we can say that,
1 mol of $NaH _2PO _4$ reacts with 2 mol of NaOH.
Molar mass of $NaH _2PO _4$  = 120 g / mol
12g of $NaH _2PO _4$ contains = 0.1 mol
So the number of moles of NaOH required = 0.2 mol
Molarity of NaOH = 1M
1 mol = 1000 ml
0.2 mol = ?
So, the volume of 1M NaOH solution = 200 ml

Which of the following has the highest melting point ?

salts salts and their classification acids, bases and salts chemistry

  1. $BeCl _2$

  2. $LiCl$

  3. $AlCl _3$

  4. $NaCl$

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Correct Option: D
Explanation:

Sodium and magnesium chlorides are solids with high melting and boiling points because of the large amount of heat which is needed to break the strong ionic attractions.
$NaCl$ having the highest melting point as the ionic bond is too strong between $Na$ and $Cl$.