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Questions Related to chemistry

Multiple choice chemistry phenomena around us changes and its classification types of changes classification of changes

Which of the following is a chemical change

  1. Burning of coal

  2. Dissolving sugar in water

  3. Dissolving salt in water

  4. Melting of ice
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A chemical change is the process in which chemical composition of the substance is changed,and physical composition may or may not changed burning of coal that is carbon(C) in presence of oxygen gives a different chemical substance $CO _2$. So, it is a chemical change. Hence option A is correct.

Multiple choice chemistry phenomena around us changes and its classification types of changes classification of changes

Melting of wax is

  1. Reversible change

  2. Irreversible change

  3. Both A,B

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In melting of wax, only the physical state of the wax changes from solid to liquid. Solid wax can be obtained from molten wax. Molten wax can be again converted to solid wax. This is an example of physical and reversible change. Hence, option A is correct.

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Which of the following statements is not correct about methanol?

  1. It is used for drinking purposes.

  2. It is highly poisonous compound.
  3. It can be prepared by reduction of formaldehyde with $LiAlH _4$

  4. It is miscible with water in all proportions.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Methanol can not be used for drinking purposes as it is highly poisonous compound.
It can be prepared by reduction of formaldehyde with $LiAlH _4$ as :
$HCHO+LiAlH _4 \rightarrow CH _3OH$
It can form hydrogen bond with water and that makes it miscible with water in all proportion.
Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Methanol can be distinguished from ethanol by the following except :

  1. Reaction with iodine and alkali
  2. Reaction with salicylic acid and ${ H } _{ 2 }{ SO } _{ 4 }$

  3. Reaction with Lucas reagent

  4. Boiling point
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lucas reagent differentiates between primary, secondary, and tertiary alcohols based on their reaction rates, but methanol and ethanol both react sluggishly or similarly under standard room conditions, making Lucas reagent ineffective for distinguishing them. The other methods, such as the iodoform test and boiling points, successfully differentiate methanol from ethanol.

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

The organic compound which when mixed with ethyl alcohol, [ethanol], makes a spurious is:

  1. methanol

  2. methanoic acid

  3. methanal

  4. ethanoic acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alcohol is used in large qualities to produce alcoholic ilquiors or beverages throughout the world. Excessive drinking of it damages kidney and produces other vices. So, to refrain people from drinking it, government controls its production and supply . This is done by making it unfit for drinking by addituion of poisonous, substances like methanol, action, pyridine, $CuSO _4.$ It is called methylated spirit/denatured alcohol. 

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Methyl alcohol is treated with conc HI and red P. The main product obtained is ?

  1. $CH _3OH$
  2. $CH _4$
  3. $CH _2I _2$
  4. $PH _3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$HI$/Red P is one of the strongest reducing agents. So, it reduces all functional groups to yield alkanes. Hence, methanol gives methane.
$CH _{3}OH \, \overset{HI/Red\, P}\rightarrow \,CH _{4}$
Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Which of the following is wood alcohol?

  1. $\displaystyle CH _{3}OH$
  2. $\displaystyle C _{2}H _{5}OH$

  3. 1-Butanol

  4. 2-Methyl -1-propanol
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha, methyl hydrate, or wood spirits, is a chemical with the formula CH₃OH.


Methanol acquired the name wood alcohol because it was once produced chiefly by the destructive distillation of wood

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

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

$(CO+H _{2})+H _{2}\overset {673k,300atm,/Cr _{2}O _{3}-ZnO} {\rightarrow}$ 
The above shown reaction may by used for manufacture of:

  1. $HCHO$
  2. $CH _{3}COOH$
  3. $HCOOH$
  4. $CH _{3}OH$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Methanol is prepared on an industrial scale from a mixture of CO and H2. The mixture is subjected to 200atm pressure and passed over ZnO and Cr2O3 catalyst at 400 to 450 degrees celsius.

Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Hydrolysis of an ester gives acid A and alcohol B. The acid reduces Fehlings solution. Oxidation of alcohol B gives acid A. The ester is:

  1. Mehthyl formate

  2. Ethyl formate

  3. Methyl acetate

  4. Ethyl acetate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A
A:- HCOOH
B:- $CH _{3}OH$
Therefore the ester is $HCOOCH _{3}$