Carbon and Its Compound | Q & A | Class X

Q1: Carbon does not make compounds by donating or accepting electrons. Why?

Answer: Carbon has four electrons in its outermost shell. To complete an octet it needs to gain four electrons. If it gains four electrons then 6 protons in its nucleus shall be unable to balance 10 electrons. On the other hand, removing four electrons from carbon atom would involve a large amount of energy; which is not possible in the practical situation. Due to this, carbon does not make compounds by donating or accepting electrons.

Q2: Covalent compounds are bad conductors of electricity. Why?

Answer: Covalent compounds do not dissociate into ions in aqueous solution. Hence, covalent compounds are bad conductors of electricity.

Q3: Covalent compounds usually have low melting and boiling points. Why?  :
Answer: In covalent compounds, the force of attraction between molecules is weak. Due to this, melting and boiling points of covalent compounds are low.
Brainstorming Session

Q4: The first member of alkane has one carbon atom but there is no alkene with the single carbon atom. Why?

Answer: Carbon has four valencies. So, it needs four monovalent atoms to make a compound. In the case of methane (first member of alkane); four hydrogen atoms satisfy all the valencies of carbon. But in the case of alkene; the first member will have 2 hydrogen atoms according to its generic formula CnH2n. Those two atoms of hydrogen will not satisfy all the valencies of carbon. Hence, such a molecule is not possible. Hence, the first member of alkene has two carbon atoms and it is known as ethane (C2H4).

Q5: Ethanol contains 2 atoms of carbon, while hexanol contains 6 atoms of carbon. Yet they show similar chemical properties. Why?

Answer: In ethanol and hexanol; the functional group is – OH. We know that functional group is responsible for chemical properties of an organic compound and all members of a homologous series show similar chemical properties. Hence, ethanol and hexanol show similar chemical properties.

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