Chemistry Questions

Q:

An atom has 7 electrons in its M - shell and contains 18 neutrons in its nucleus. What is its mass number

A) 25 B) 27
C) 35 D) 43
 
Answer & Explanation Answer: C) 35

Explanation:

According to Bohr model, Each shell can occupy 2n2 electrons in their orbits where n=1,2,3.. for K,L,M,..

 

The atom has 2 electrons in k, 8 electrons in L and 7 electrons in M = 2 + 8 + 7 = 17

 

And given that its nucleus has 18 neutrons

 

=> its mass number = number of (electrons + neutrons ) = 17 + 18 = 35

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

45 9761
Q:

What is the conjugate base of H2O?

A) NH3+ B) OH-
C) H2O D) All the above
 
Answer & Explanation Answer: B) OH-

Explanation:

A conjugate acid, is a species formed by the reception of a proton (H+) by a base—in other words, it is a base with a hydrogen ion added to it.

On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid.

Because some acids are capable of releasing multiple protons, the conjugate base of an acid may itself be acidic.

Represented as the following chemical reaction:

Acid + Base ⇌ Conjugate Base + Conjugate Acid

 

The water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium. On the other hand, ammonia is the conjugate base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. We can also refer to OH- as a conjugate base of H2O, since the water molecule donates a proton towards the production of NH+4 in the reverse reaction, which is the predominating process in nature due to the strength of the base NH3 over the hydroxide ion.

 

Report Error

View Answer Report Error Discuss

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

4 9747
Q:

The bleeding of a wound is stopped by the application of ferric chloride because_____

A) Ferric chloride seals the blood vessels B) Blood starts flowing in the opposite direction
C) Blood reacts and a solid is formed which seals the blood vessels D) Blood is coagulated and the blood vessels are sealed
 
Answer & Explanation Answer: D) Blood is coagulated and the blood vessels are sealed

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

36 9702
Q:

Li3PO4 compound name?

A) Lithium perchlorate B) Lithium phyrite
C) Lithium phosphate D) None
 
Answer & Explanation Answer: C) Lithium phosphate

Explanation:

The given compund Li3PO4 name is Lithium phosphate.

 

Lithium phosphate is a white crystal at room temperature. It is slightly soluble in water.

It  can be used to produce glass, disk, colorful phosphor powder. It can also be used as a catalyst in some reactions.

Report Error

View Answer Report Error Discuss

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

5 9614
Q:

The freezing point of water at 760mm pressure is

A) 0 K B) 273 K
C) 273 C D) -273 C
 
Answer & Explanation Answer: B) 273 K

Explanation:

K is degree kelvin

Zero K corresponds to -273  K = C + 273

The freezing point of water being 0 C, on the kelvin scale it is 0 C + 273 K

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

12 9491
Q:

Which acid is produced when milk gets sour?

A) Lactic acid B) Acetic acid
C) Tartaric acid D) Butyric acid
 
Answer & Explanation Answer: A) Lactic acid

Explanation:
Report Error

View Answer Report Error Discuss

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

11 9481
Q:

A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at :

A) 518 nm B) 1035 nm
C) 325 nm D) 743 nm
 
Answer & Explanation Answer: D) 743 nm

Explanation:

1λ=1λ1+1λ2

1355=1680+1λ2

1λ2=680-355680×355

λ2=743nm.

Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: AIEEE

12 9378
Q:

Water which is suitable for drinking is called _______________ water.

 

A) hygienic B) sparkling
C) potable D) sanitary
 
Answer & Explanation Answer: C) potable

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: Bank Exams

0 9364