Sawaal

 Chemistry Questions

Popular Latest Rated
Q:

Leakage in LP gas cylinders is easily detected by adding

A) mercaptans B) propylene
C) carbon disulphide D) phosgene
 
Answer & Explanation Answer: A) mercaptans

Explanation:

mercaptans (or thioalcohols) have a foul odour

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

7 4413
Q:

The most abundant metal in earth crust is

A) Iron B) magnesium
C) calcium D) aluminium
 
Answer & Explanation Answer: D) aluminium

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

6 4393
Q:

Chloroform used as anaesthetic should be preserved in the dark in tightly stoppered bottles because otherwise

A) it becomes coloured B) it gets evaporated in air
C) it gets oxidised to phosgene D) it gets decomposed to chloropicrin
 
Answer & Explanation Answer: C) it gets oxidised to phosgene

Explanation:

Chloroform, CHCl3 is easily oxidised to the highly poisonous gas known as phosgene or carbonyl chloride COCl2. Hence if it is used as anaesthetic it should be kept free from sunlight and air.

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: AIEEE

9 4359
Q:

Which reaction occurs spontaneously?

A) Cl2(g) + 2NaF(aq)--> F2(g) + 2NaCl(aq) B) I2(s) + 2NaF(aq)--> F2(g) + 2NaI(aq)
C) Cl2(g) + 2NaBr(aq)-->Br2(l) + 2NaCl(aq) D) I2(s) + 2NaBr(aq)--> Br2(l) + 2NaI(aq)
 
Answer & Explanation Answer: C) Cl2(g) + 2NaBr(aq)-->Br2(l) + 2NaCl(aq)

Explanation:

In this chemical reaction chlorine change oxidation number from 0 to -1 (reduction) and bromine change oxidation number from -1 to 0 (oxidation).

Chlorine is stronger oxidation reagent than bromine.

In VIIA or group 17 (halogen elements) there are six elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At) and tennessin(Ts).

They have high electronegativity because they have seven valence electrons in their outermost energy level, so they can gain an electron to have the octet rule.  

Going down in the group, element are weaker oxidazing reagent and less reactive.

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Analyst , Bank Clerk , Bank PO

2 4341
Q:

Which one of the following can be oxidised to the corresponding carbonyl compound:

A) 2-methyl-2-hydroxy propane B) 2-hydroxy propane
C) o-Nitrophenol D) Phenol
 
Answer & Explanation Answer: B) 2-hydroxy propane

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: AIEEE

12 4325
Q:

The atoms of the elements having same mass number but different atomic number are called

A) Isotopes B) Isobars
C) Isotones D) Isomers
 
Answer & Explanation Answer: B) Isobars

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

6 4308
Q:

Of the following radiations, the most easily stopped by air

A) alpha - rays B) beta - rays
C) gamma -rays D) x - rays
 
Answer & Explanation Answer: A) alpha - rays

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

2 4281
Q:

Which one of the following laws explain the formation of carbon monoxide and carbon dioxide from carbon and oxygen

A) Laws of conservation of mass B) Laws of multiple proportion
C) Laws of reciprocal proportions D) Law of definite proportions
 
Answer & Explanation Answer: B) Laws of multiple proportion

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

5 4275