LIVE Course for free

Rated by 1 million+ students
Get app now
0 votes
in Chemistry by (30.0k points)
closed by
Correct order of Acidic strength is :
1. CH4 > NH3 > H2O > HF
2. HF > H2O > CH4 > NH3
3. CH4 < NH3 < H2O < HF
4. HF > CH4 > H2O > NH3

1 Answer

0 votes
by (30.0k points)
selected by
Best answer
Correct Answer - Option 3 : CH4 < NH3 < H2O < HF


  • Consider the given compounds CH4, NH3, H2O and  HF . These all are hydrides of first row elements in the periodic table.
  • When we compare the compounds in the same horizontal row of the periodic table, the dominant factor becomes the electronegativity of the atom bond to the hydrogen.
  • It is because the electron density is shifted towards the highly electronegative element, which facilitates the release of the H+ ion. 
  • We know that the electronegativity increases across a row in the periodic table from left to right. 
  • Here, the relative electronegativities is in the order C < N < O <
  • Because fluorine is the most electronegative element, the bond H-F is more polarized, and the proton in HF is the most positive. So, H-F is most acidic. 

The increasing order of acidic strength of the given hydrides are given by CH4 < NH3 < H2O < HF

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.