Chemistry Questions

Q:

What is the oxidation number of carbon in NaHCO3?

A) -4 B) -3
C) +4 D) +2
 
Answer & Explanation Answer: C) +4

Explanation:

The given compound is NaHCO3 Sodium bicarbonate which is commonly known as Baking soda.

Oxidation numbers are the charges on ions. When a neutral atom loses electrons it becomes positively charged. When a neutral atom gains electrons it becomes negatively charged.

 

Here the C represents the oxidation state of carbon in this compound. Compounds are electrically neutral, which is why we set the sum of the oxidation states equal to zero.

Sodium has a +1 oxidation state. Hydrogen has a +1 oxidation state. Oxygen has a -2 oxidation state. There are three oxygen atoms, which means the total oxidation state provided by both oxygen ions is -6. Adding up these oxidation states we get:

1 + 1 + (-6) + C = 0

-4 + C = 0

=> C = 4


This means the oxidation state of carbon in this compound is +4.

Report Error

View Answer Report Error Discuss

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

1 5502
Q:

Neutron was discovered by

A) J.J.Thomson B) Chadwick
C) Rrutherford D) Priestley
 
Answer & Explanation Answer: B) Chadwick

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

8 5441
Q:

Select the correct statement (s).

A) When energy is transferred to the system from the surrounding as work, the surrounding do work on the system and the value of work (W) positive. B) When energy is transferred from the system to the surrounding as work, work is done on the surrounding and the value of W is negative.
C) Both (A) and (B) D) None of the above
 
Answer & Explanation Answer: C) Both (A) and (B)

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry
Exam Prep: AIEEE

13 5432
Q:

Which ionization process requires the most energy?

A) C3+ (g) → C4+ (g) + e- B) C (g) → C+ (g) + e-
C) C2+ (g) → C3+ (g) + e- D) C+ (g) → C2+ (g) + e-
 
Answer & Explanation Answer: A) C3+ (g) → C4+ (g) + e-

Explanation:

We know that each successive IE is greater than the previous one, because each ionization process removes one electron and hence increases the total attractive force on the remaining electrons from the nucleus. Hence, C3+ (g) → C4+ (g) + e- needs more energy.

Report Error

View Answer Report Error Discuss

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

1 5377
Q:

The element common to all acids is

A) Hydrogen B) Oxygen
C) carbon D) Sulphur
 
Answer & Explanation Answer: A) Hydrogen

Explanation:

Hydrogen is the common element in all acids.

Report Error

View Answer Report Error Discuss

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

4 5367
Q:

The alpha-particles are

A) high energy electrons B) positively charged hydrogen irons
C) high energy x ray radiations D) double positively charged helium nuclei
 
Answer & Explanation Answer: D) double positively charged helium nuclei

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Chemistry

6 5358
Q:

Intermolecular forces in HCl are

A) Hydrogen bonding B) Dipole-dipole
C) Dispersion force D) All the above
 
Answer & Explanation Answer: D) All the above

Explanation:

Intermolecular forces :

The forces of attraction present in between the molecules or atoms or compounds is termed as intermolecular forces.


The molecule HCl is composed of hydrogen and chlorine atom. There is high difference in electronegativities therefore, it is polar in nature. The H end of HCl is permanently slightly positive charge. The Cl end of HCl has a permanent slight negative charge. the "H" in one molecule is attracted to the "Cl" in a neighbor. The intermolecular force is weak compared to a covalent bond. But this dipole-dipole interaction is one of the stronger intermolecular attractions.

It also has hydrogen bonding and dispersion forces. 

Dispersion forces are the weakest forces which are present in between all molecules or atoms.
Hydrogen bonds are present in molecules having at least one H-A bond where A is the strong electronegative atom (mainly F, Cl and N).

Report Error

View Answer Report Error Discuss

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

4 5352
Q:

A yellow element that stinks when burned

A) Sulphur B) Chlorine
C) Fluorine D) Bromine
 
Answer & Explanation Answer: A) Sulphur

Explanation:

Sulphur is an yellow element that stinks when burned.

Report Error

View Answer Report Error Discuss

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

3 5343