Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

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

State whether true or false :

Ropes made by rayon are used in cranes and elevators.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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
Multiple choice chemistry substances in daily use polyester and acrylic rayon and nylon synthetic fibres

Ropes made of _______ are used in cranes and lifts.

  1. rayon

  2. nylon

  3. acrylic

  4. spandex
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Name the plastic whose sheets are used for packing liquids.

  1. Polythene

  2. Polycot

  3. Polywool

  4. Polyester
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $\text{A}$
Multiple choice salts salts and their classification acids, bases and salts chemistry

Which of the following does NOT form an acidic salt?

  1. Phosphoric acid

  2. Carbonic acid

  3. Hydrochloric acid

  4. Sulphuric
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An acidic salt is formed by the partial replacement of replaceable hydrogen ions from a polybasic acid. Carbonic acid (H2CO3) is a weak acid that typically dissociates completely or forms neutral salts, whereas others like phosphoric or sulphuric acids have multiple replaceable hydrogens allowing for acidic salt formation.

Multiple choice salts salts and their classification acids, bases and salts chemistry

Lime water + sulphuric acid $\rightarrow$

  1. Heat + Calcium sulphate

  2. Water + Heat

  3. Calcium sulphate + Water + Heat

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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).

Multiple choice salts salts and their classification acids, bases and salts chemistry

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

  1. Conductivity

  2. Calorimetry

  3. Precipitation

  4. Spectrophotometry
Reveal answer Fill a bubble to check yourself
C Correct answer
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).

Multiple choice salts salts and their classification acids, bases and salts chemistry

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

  1. yellow

  2. white

  3. red

  4. black
Reveal answer Fill a bubble to check yourself
B Correct answer
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).

Multiple choice salts salts and their classification acids, bases and salts chemistry

${ H } _{ 3 }{ PO } _{ 4 }$ 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)

  1. 100 mL

  2. 200 mL

  3. 80 mL

  4. 300 mL
Reveal answer Fill a bubble to check yourself
B Correct answer
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

Multiple choice salts salts and their classification acids, bases and salts chemistry

Which of the following has the highest melting point ?

  1. $BeCl _2$
  2. $LiCl$
  3. $AlCl _3$
  4. $NaCl$
Reveal answer Fill a bubble to check yourself
D Correct answer
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 $Cl$.