Question map
Not attempted Correct Incorrect ★ Bookmarked
Loading…
Q12 (NDA-II/2018) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

The atomic number of an element is 8. How many electrons will it gain to form a compound with sodium?

Result
Your answer: —  Â·  Correct: B
Explanation

The element with atomic number 8 is oxygen [1]. Its electronic configuration is 2, 6, meaning it has six electrons in its outermost (L) shell [1]. To achieve a stable noble gas configuration (an octet), oxygen requires two additional electrons [1]. Sodium, with atomic number 11, has one electron in its outermost shell and tends to lose it to form a Na+ cation [2]. When sodium reacts with oxygen to form an ionic compound like sodium oxide (Na2O), each sodium atom loses one electron, and the oxygen atom gains a total of two electrons to form an O2- anion. This transfer allows oxygen to complete its valence shell, attaining the stable configuration of neon. Therefore, oxygen gains two electrons to bond with sodium.

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.1 BONDING IN CARBON – THE COVALENT BOND > p. 60
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.3 HOW DO METALS AND NON-METALS REA ALS REACT? > p. 47
How others answered
Each bar shows the % of students who chose that option. Green bar = correct answer, blue outline = your choice.
Community Performance
Out of everyone who attempted this question.
100%
got it right
✓ Thank you! We'll review this.

SIMILAR QUESTIONS

CDS-I · 2025 · Q53 Relevance score: -0.54

If atomic number of an element is 11, the correct name, symbol and valency are :

NDA-II · 2016 · Q14 Relevance score: -1.86

There are six electrons, six protons and six neutrons in an atom of an element. What is the atomic number of the element ?

NDA-I · 2022 · Q34 Relevance score: -1.95

For an element with atomic number 35, which one of the following will be the correct number of electrons in its valence shell based on Bohr’s model of an atom?

CDS-I · 2017 · Q18 Relevance score: -2.41

What is the number of atoms in 46 g of sodium-23 (iV=Avogadro constant)?

NDA-II · 2014 · Q50 Relevance score: -3.14

Which of the following element combinations will form ionic compounds? 1. Ca {Z = 20) and Ti (Z = 22) 2. Si (Z = 14) and Br [Z = 35) 3. Mg [Z = 12) and Cl {Z = 17) Select the correct answer using the code given below.