Punjab Board Class 10 Science — Important Questions 2026

During the electrolysis of water (with dilute H₂SO₄), gas is collected at both electrodes. The ratio of the volume of gas at the cathode to the volume at the anode is 2:1. Which gas is collected at the cathode and why is its volume double?

In the reaction: Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq), a white precipitate is formed. Which ion combination causes the precipitate, and what type of reaction is this?

Chips manufacturers flush bags of chips with nitrogen gas before sealing. Which scientific principle is being applied here and why is nitrogen specifically used?

A magnesium ribbon is burnt in oxygen to produce magnesium oxide. The balanced equation is: 2Mg + O₂ → 2MgO. Which of the following correctly identifies the type(s) of reaction occurring?

Which ion is responsible for the acidic nature of all acids in aqueous solution?

A student performs a neutralisation reaction by adding dilute HCl to NaOH solution containing phenolphthalein. What colour change will the student observe when the acid exactly neutralises the base?

The chemical name of baking soda is:

Which process is used to manufacture sodium hydroxide from brine (aqueous NaCl solution)?

The correct order of reactivity of metals with water, from most reactive to least reactive, is:

Hydrogen gas is NOT evolved when a metal reacts with dilute nitric acid (HNO₃) because:

In the reactivity series, which of the following is the correct arrangement from most reactive to least reactive?

A metal X displaces metal Y from its salt solution. This means: