ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 2 marks · Very short answer

CBSE Class 10 Science 2025: question 22(A)

Set in the CBSE Class 10 board exam of 2025, paper 31/4/1, section B, question 22(A), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q22(A) · 2 marks · Very short answerMetals and Non-metals

Show the formation of magnesium chloride by electron transfer. Write the name of the cation and anion present in the compound formed. (Atomic Number of Mg = 12, Cl = 17)

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/4/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Write the electronic configurations of Mg and Cl first.

Hint 2

Mg has 2 valence electrons and each Cl needs only 1. How many Cl atoms does one Mg need?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

Electronic configurations: Mg (12) = 2, 8, 2; Cl (17) = 2, 8, 7.
Mg gives one valence electron to each of two Cl atoms, so that every ion gets a complete octet:
$M g^{\times\times} + 2 \cdot \ddot{.. Cl} : \to M g^{2 +} + 2 [^{\times} \ddot{.. Cl} :]^{-}$
That is, $Mg \to M g^{2 +} + 2 e^{-}$ and $2Cl + 2 e^{-} \to 2C l^{-}$ , which together give $MgC l_{2}$ (that is, $M g^{2 +} (C l^{-})_{2}$ ).
1 mark
Cation: magnesium ion, $M g^{2 +}$ .
½ mark
Anion: chloride ion, $C l^{-}$ .
½ mark

Answer: $Mg \to M g^{2 +} + 2 e^{-}$ , $2Cl + 2 e^{-} \to 2C l^{-}$ , giving $MgC l_{2}$ ; cation $M g^{2 +}$ , anion $C l^{-}$ .

Where the marks are

Shows the transfer of two electrons from Mg to two Cl atoms forming $MgC l_{2}$ (1 mark)
Names the cation as the magnesium ion, $M g^{2 +}$ (½ mark)
Names the anion as the chloride ion, $C l^{-}$ (½ mark)

Revise the chapter

Chapter: Metals and Non-metals (notes, formulas, where marks are lost and every past question)
Topic: Ionic Compounds: Formation and Properties

Practise this chapterBoard-style questions from Metals and Non-metals, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 31/4/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.

CBSE Class 10 Science 2025: question 22(A)

Hints

Step-by-step solution

Revise the chapter

More questions from Metals and Non-metals