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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.
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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]
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
Choose the correct answer from the options given below
Which one is coordinate molecule?
What is the term defined below?
A bond formed by a shared pair of electrons with both electrons coming from the same atom.
By drawing an electron dot diagram, show the lone pair effect leading to the formation of ammonium ion from ammonia gas and hydrogen ion.
Bonding in this molecule can be understood to involve coordinate bonding.
Identify the following:
A bond formed between two atoms by sharing of a pair of electrons, with both electrons being provided by the same atom.
