The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, to attain a noble gas configuration. This may be either through gain of electrons or loss of electrons or sharing of electrons.

(a) An element A has atomic number 16, how will it attain its nearest noble gas configuration?

(b) Write the number of (i) single and (ii) double covalent bonds in a molecule of butene ( $C_4H_8$ ).

(c) (A) Explain the formation of a molecule of ammonia ( $NH_3$ ), using electron dot structure. (Atomic number of nitrogen is 7)

OR

(c) (B) Why does carbon share its valence electrons with other atoms of carbon or with atoms of other elements?

Q: The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, to attain a noble gas configuration. This may be either through gain of electrons or loss of electrons or sharing of electrons. (a) An element A has atomic number 16, how will it attain its nearest noble gas configuration? (b) Write the number of (i) single and (ii) double covalent bonds in a molecule of butene ($C_4H_8$). (c) (A) Explain the formation of a molecule of ammonia ($NH_3$), using electron dot structure. (Atomic number of nitrogen is 7) OR (c) (B) Why does carbon share its valence electrons with other atoms of carbon or with atoms of other elements?

(a) An element A with atomic number 16 will attain its nearest noble gas configuration by gaining two electrons to form $A^{2-}$. (b) (i) The number of single covalent bonds in a molecule of butene ($C_4H_8$) is 7. (ii) The number of double covalent bonds in a molecule of butene ($C_4H_8$) is 1. (c) (A) The formation of a molecule of ammonia ($NH_3$) can be explained using electron dot structure as follows: $N \cdot \cdot \cdot \cdot \cdot \cdot + 3H \cdot \rightarrow N : H : H : H$ OR (c) (B) Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements because it has four electrons in its outermost shell and needs to gain or lose four electrons to attain noble gas configuration.

Q: How many marks does this question carry in CBSE Class 10 Science 2025?

This question carries 4 marks in the CBSE Class 10 Science 2025 examination.

Q: Which chapter does this question come from in Science?

This question is from the chapter "Carbon and its Compounds" in the CBSE Class 10 Science syllabus.

Q: What topic does this question cover in Science?

This question covers the topic "Carbon and its Compounds" from CBSE Class 10 Science.

Q: What type of question is this in the CBSE Class 10 Science 2025 paper?

This question appears in Section E in the CBSE Class 10 Science 2025 paper.

Question

The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, to attain a noble gas configuration. This may be either through gain of electrons or loss of electrons or sharing of electrons.

(a) An element A has atomic number 16, how will it attain its nearest noble gas configuration?

(b) Write the number of (i) single and (ii) double covalent bonds in a molecule of butene ( $C_4H_8$ ).

(c) (A) Explain the formation of a molecule of ammonia ( $NH_3$ ), using electron dot structure. (Atomic number of nitrogen is 7)

OR

(c) (B) Why does carbon share its valence electrons with other atoms of carbon or with atoms of other elements?

Analysis & Explanation

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