Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

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

Spandex is used in garments because :

  1. elasticity.

  2. strength.

  3. biodegradable.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

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

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

Which of the following is true?

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

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

The fruits of cotton plants are called:

  1. calotropis

  2. cotton bolls

  3. xanthiun

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. Thermoplastics

  2. Fibres

  3. Thermosetting polymers

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

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

Weaving is the process of 

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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 :

  1. 2

  2. 0.5

  3. 4

  4. 1
Reveal answer Fill a bubble to check yourself
B Correct answer
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)
$\\ or,\quad 2={ \left( 4 \right)  }^{ x }\\ or,\quad 2={ { 2 }^{ 2 } }^{ x }\\ or,\quad 2x=1\\ or,\quad x=\cfrac { 1 }{ 2 } \\ x=0.5$
Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

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

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

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

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:

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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 $(D)$