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Question
Give reason for the following:
Covalent compounds have a low melting and boiling point.
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Solution
Covalent compounds are held together by modest intramolecular forces. As a result, breaking the bonds between two or more molecules requires only a minimal amount of energy.
Therefore, these compounds have low melting and boiling points.
RELATED QUESTIONS
Identify the term/substance in the following:
The electrons present in the outermost shell of an atom.
By drawing an electron dot diagram show the formation of Ammonium ion [Atomic No.: N = 7 and H = 1]
Identify the anion present in the following compounds:
A salt M on treatment with concentrated sulphuric acid produces a gas which fumes in moist air and gives dense fumes with ammonia
The following table shows the test a student performed on four different aqueous solutions which are X, Y, Z and W. Based on the observations provided, identify the cation present:
| Chemical test | Observation | Conclusion |
| To solution X, ammonium hydroxide is added in minimum quantity first and then in excess |
A dirty white precipitate is formed which dissolves in excess to form a clear solution |
(1) |
| To solution Y ammonium hydroxide is added in the minimum quantity first and then in excess |
A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution. |
(2) |
| To solution W a small quantity of sodium hydroxide solution is added and then in excess. |
A white precipitate is formed which remains insoluble. |
(3) |
| To a salt Z calcium hydroxide the solution is added and then heated. |
A pungent smelling gas turning moist red litmus paper blue is obtained. |
(4) |
Choose the correct answer from the options given below:
A compound X consists of only molecules. Hence, X will have
A. A crystalline hard structure
B. A low melting point and low boiling point
C. An ionic bond
D. A strong force of attraction between its molecules
Give two example in the following case:
Co-ordinate bond compounds
What is meant by the term chemical bonding?
Fill in the blank
Coordinate bond is also called __________bond.
What is a lone pair of electrons?
By drawing an electron dot diagram, show the lone pair effect leading to the formation of the ammonium ion from ammonia gas and hydrogen ion.
