Which of the following pairs will form an ionic bond? MCQ with Answer and Explanation

Which of the following pairs will form an ionic bond?
A. Hydrogen and chlorine
B. Carbon and oxygen
C. Potassium and fluorine
D. Nitrogen and hydrogen
Answer: Option C
Solution (By JKExamLibrary)
Potassium (metal, low EN) and fluorine (most electronegative non-metal) have large EN difference (~3.2), leading to electron transfer and ionic bond (KF). Carbon-oxygen form polar covalent (CO₂). H-Cl polar covalent. Nitrogen-hydrogen covalent (NH₃). Ionic bonds form between metals of Group 1, 2 and non-metals of Group 16, 17.

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Practice More chemistry Questions

Question #1
The pH of a solution is 4.5. What is the nature of the solution?
A. Basic
B. Neutral
C. Weakly acidic
D. Strongly acidic

Correct Answer: Option C


Explanation:
pH < 7 indicates acidic. Since 4.5 is less than 7 but not extremely low (like 1-2), it is weakly acidic. Neutral pH=7, basic pH>7. A solution with pH 4 is more acidic than pH 5.

This question belongs to: Science chemistry
Question #2
Which of the following reactions is an example of a Wurtz reaction?
A. CH3Cl + Na -> C2H6 + NaCl
B. 2CH3Cl + Zn -> C2H6 + ZnCl2
C. CH3Cl + KOH(aq) -> CH3OH + KCl
D. CH3Cl + KOH(alc) -> CH4 + KCl

Correct Answer: Option A


Explanation:
The Wurtz reaction involves the reaction of an alkyl halide with sodium metal in dry ether to form a higher alkane. For example, two molecules of methyl chloride react with two sodium atoms to form ethane (C2H6) and sodium chloride. It is primarily used to synthesize symmetrical alkanes with an even number of carbon atoms.

This question belongs to: Science chemistry
Question #3
Permanent hardness of water is caused by:
A. Bicarbonates of Ca and Mg
B. Chlorides and sulfates of Ca and Mg
C. Potassium sulfate
D. Sodium chloride

Correct Answer: Option B


Explanation:
Permanent hardness is due to CaCl₂, CaSO₄, MgCl₂, MgSO₄. These do not precipitate on boiling. Temporary hardness (bicarbonates) is removed by boiling. Both can be removed by ion exchange or washing soda.

This question belongs to: Science chemistry