Tag: chemistry

Questions Related to chemistry

Synthetic fibres are also called as :

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. rayon fibres

  2. artificial or human made fibres

  3. natural fibres

  4. collective fibres

Show answer
Correct Option: B
Explanation:

Synthetic fibres are also called as artificial or human made fibres since they are made by human in factories.

Spandex is used in garments because :

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. elasticity.

  2. strength.

  3. biodegradable.

  4. Both A and B.

Show answer
Correct Option: D
Explanation:

Spandex, Lycra or elastane is a synthetic fiber known for its exceptional elasticity. It is stronger and more durable than natural rubber. Because of its elasticity and strength (stretching up to five times its length), spandex has been incorporated into a wide range of garments, especially in skin-tight garments. A benefit of spandex is its significant strength and elasticity and its ability to return to the original shape after stretching and faster drying than ordinary fabrics.

Which of the following can define molecules in the liquid state?

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. Molecules vibrating in a fixed position and held in place by strong forces

  2. Molecules can rotate and roll over each other because the forces are moderately strong

  3. Molecules can move anyway in random because there are no forces holding the molecules together

  4. A state of matter which contains only charged particles

Show answer
Correct Option: B
Explanation:

In liquid, particles are loosely bound together by intramolecular forces. Unlike a solid, liquid has no fixed shape but instead has a characteristic readiness to flow and therefore takes on the shape of any container.

Forces between them are moderately strong as compare to solid.

Hence, option $B$ is correct. 

Which of the following is true?

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. Cellulose is made up of glucose units.

  2. Weaving and knitting are two process to get plastic.

  3. Plastics get corroded easily.

  4. Plastics are not polymers.

Show answer
Correct Option: A
Explanation:

Cellulose is made up of glucose units by glycosidic bonds.

Weaving and knitting are used to make silk fiber.
Plastic is non-corrosive and it is a polymer of the various compound.
Example: PVC, bakelite, etc.

The fruits of cotton plants are called:

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. calotropis

  2. cotton bolls

  3. xanthiun

  4. none of the above

Show answer
Correct Option: B
Explanation:

Cotton bolls.

The fruit, called bolls, then begin to develop. These green, immature bolls are a segmented pod containing approximately 32 immature seeds from which the cotton fibres  will grow. The boll is considered a fruit because it contains seeds.

In which of the following, polymer chains are held with hydrogen bonds?

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. Thermoplastics

  2. Fibres

  3. Thermosetting polymers

  4. Elastomers

Show answer
Correct Option: B
Explanation:

$Fibres$ are the thread forming solids which possess high strength and high modulus. This characteristic is attributed to the strong intermolecular forces like hydrogen bonding.

Weaving is the process of 

chemistry fibre to fabric: plant fibre classification of fibres fibres history of fabric

  1. Separating seeds from cotton bolls

  2. Spinning of yarn

  3. Arranging two sets of yarn together to make a fabric

  4. Immersing stems of jute plant in water

Show answer
Correct Option: C
Explanation:

Weaving is a method of textile production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric or cloth. Cloth is made by crossing two sets of threads over and under each other. The two sets of threads are called warp and weft.

Therefore, the correct answer is option C.

For a chemical reaction, $A \rightarrow products$, the rate of reaction doubles when the concentration of A is increased by a factor of 4, the order of reaction is :

chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

  1. 2

  2. 0.5

  3. 4

  4. 1

Show answer
Correct Option: B
Explanation:
let x be order of reaction and K be rate of constant.
* A$\rightarrow $ products.
$ \cfrac { K\cfrac { { \left( A \right)  }^{ x } }{ time }  }{ K\cfrac { { \left( 4A \right)  }^{ x } }{ time }  } or,\quad \cfrac { 1 }{ 2 } = { \left( \cfrac { A }{ 4A }  \right)  }^{ x }\\ or,\quad \cfrac { 1 }{ 2 } ={ \left( \cfrac { 1 }{ 4 }  \right)  }^{ x }$      (reciprocating)
$\\ or,\quad 2={ \left( 4 \right)  }^{ x }\\ or,\quad 2={ { 2 }^{ 2 } }^{ x }\\ or,\quad 2x=1\\ or,\quad x=\cfrac { 1 }{ 2 } \\ x=0.5$

The term $-\dfrac{dc}{dt}$ in a rate equation refers to:

chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

  1. the concentration of a reactant

  2. the decrease in concentration of the reactant with time

  3. the velocity constant of reaction

  4. none of the above

Show answer
Correct Option: B
Explanation:

The term $-\dfrac{dc}{dt}$ in a rate expression indicates the decrease in concentration of the reactant with time. It is the minus sign which is used to show the decrease in concentration of the reactant.

For a first order reaction, A$\rightarrow$ products, the concentration of A changes from $0.1$M to $0.025$ M $80$ minutes. The rate of reaction when the concentration of A is $0.01$M, is:

chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

  1. $1.73\times 10^{-5}$M/min

  2. $3.47\times 10^{-4}$M/min

  3. $3.47\times 10^{-5}$M/min

  4. $1.73\times 10^{-4}$M/min

Show answer
Correct Option: D
Explanation:

K$= \frac { 2.303 }{ t } \log { \left[ \dfrac { { A } _{ 0 } }{ A }  \right]  } $


$\quad =\dfrac { 2.303 }{ 80 } \log [{ \dfrac { 0.1 }{ 0.025 }  }]$

$k= 0.0173\quad { min }^{ -1 }$

$\therefore $ Rate$= K\left[ A \right]$

$\quad \quad \quad =0.0173\left[ 0.01 \right]$

$\quad \quad \quad = 1 .73 \times { 10 }^{ -4 } $

$\quad \quad \quad =1.73\times{ 10 }^{ -4 }M/min$

Hence, the correct option is $(D)$