(English Medium) ICSE Class 9 - CISCE Question Bank Solutions

State the methods by which hydrated salts can be made anhydrous.

What are hydrous substances? Explain with examples.

Name three methods by which hydrous substances can be made anhydrous.

How does number of valence electrons vary on moving from left to right in the third period of a periodic table?

Sodium and aluminum have atomic numbers 11 and 13, respectively. They are separated by one element in the periodic table and have valencies 1 and 3 respectively. Chlorine and potassium are also separated by one element in the periodic table (their atomic numbers being 17 and 19, respectively) and yet both have valency 1. Explain.

Compare hydrogen with alkali metals on the basis of:

Oxide formation 

In what respect does hydrogen differ from:

alkali metals

Give the general group study of hydrogen with reference to

burning

Give the general group study of hydrogen with reference to

reducing power 

Compare hydrogen and halogens on the basis of:

reaction with oxygen 

Why this reaction is considered a reversible reaction?

Why zinc and aluminium are considered to have a unique nature. Give balanced equations to support your answer.

Describe briefly the ionic concept of oxidation and reduction. Give an equation to illustrate.

Is it essential that oxidation and reduction must occur side by side in a chemical reaction? Explain

State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.

PbO + CO → Pb + CO₂

State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.

Mg + 2HCl → MgCl₂ + H₂

State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.

H₂S + Cl₂→ 2HCl + S

State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.

Cl₂ + H₂S → 2HCl + S 

State whether the following conversion is oxidation or reduction:

PbO₂ + SO₂→ PbSO₄ 

State whether the following conversion is oxidation or reduction:

Cu²⁺ + 2 e^-→ Cu