NCERT Exemplar Solutions
Class 7 - Mathematics - Unit 1: Number System - Problems and Solutions
Question 111

Question. 111

111. An atom becomes an ion if it loses or gains electrons. The ion charge is (sum of proton charges) + (sum of electron charges). Complete the table.

Name of IonProton ChargeElectron ChargeIon Charge
Hydroxide ion+9−1
Sodium ion+11+1
Aluminium ion+13−10
Oxide ion+8−10

Answer:

Name of IonProton ChargeElectron ChargeIon Charge
Hydroxide ion+9−10−1
Sodium ion+11−10+1
Aluminium ion+13−10+3
Oxide ion+8−10−2

Detailed Answer with Explanation:

Ion charge = (proton total) + (electron total).

Hydroxide: 9 + (−10) = −1; Sodium: 11 + (−10) = +1; Aluminium: 13 + (−10) = +3; Oxide: 8 + (−10) = −2.

NCERT Exemplar Solutions Class 7 – Mathematics – Unit 1: Number System – Problems and Solutions | Detailed Answers