Home / IB DP Chemistry -Structure 1.1 Introduction to the particulate nature of matters – IB Style Questions For HL Paper 1A

IB DP Chemistry -Structure 1.1 Introduction to the particulate nature of matters - IB Style Questions For HL Paper 1A -FA 2025

IBDP Chemistry HL Paper 1A & 1B - All Chapters

Question 

What is the name of this change of state?

\( \mathrm{CO_2(g)\rightarrow CO_2(s)} \)

(A) Condensation
(B) Deposition
(C) Sublimation
(D) Freezing
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathrm{B}} \)

The change shown is directly from a gas to a solid:

\( \mathrm{CO_2(g)\rightarrow CO_2(s)} \)

A change of state from gas directly to solid is called deposition.

Condensation is gas to liquid, sublimation is solid to gas, and freezing is liquid to solid.

Therefore, the correct answer is (B).

Question 

Which methods for separating the given mixtures into their components are correct?

MixtureMethod
I. A mixture of a solid in a liquid in which solubility of the solid varies with temperatureCrystallization
II. A mixture of a solid in a liquid in which the solid is not dissolvedFiltration
III. A mixture of two miscible liquids with different boiling pointsDistillation
(A) I and II only
(B) I and III only
(C) II and III only
(D) I, II and III
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathrm{D}} \)

I. Crystallization: Correct. Crystallization is used to separate a dissolved solid from a solution when its solubility changes significantly with temperature.

II. Filtration: Correct. Filtration separates an insoluble solid from a liquid.

III. Distillation: Correct. Distillation can separate miscible liquids with different boiling points.

Therefore, all three methods are correct, so the answer is (D).

Question

What is the sum of the coefficients when the equation is balanced with the lowest whole number ratio?
\[ \_\ \text{Na}_2\text{S}_2\text{O}_3(aq) + \_\ \text{HCl}(aq) \;\longrightarrow\; \_\ \text{S}(s) + \_\ \text{SO}_2(g) + \_\ \text{NaCl}(aq) + \_\ \text{H}_2\text{O}(l) \]
A.  \(6\)
B.  \(7\)
C.  \(8\)
D.  \(9\)
▶️ Answer/Explanation
Detailed solution

Begin with sodium. In \(\text{Na}_2\text{S}_2\text{O}_3\), there are \(2\) sodium atoms. To balance sodium, place a coefficient of \(2\) in front of \(\text{NaCl}\).

\[ \text{Na}_2\text{S}_2\text{O}_3 + \text{HCl} \rightarrow \text{S} + \text{SO}_2 + 2\text{NaCl} + \text{H}_2\text{O} \]

Sulfur: The left side has \(2\) sulfur atoms; the products have \(1\) in \(\text{S}\) and \(1\) in \(\text{SO}_2\). Oxygen: The left has \(3\); the right has \(2\) (in \(\text{SO}_2\)) and \(1\) (in \(\text{H}_2\text{O}\)), so oxygen is balanced.

Hydrogen: The product side has \(2\) hydrogens (in \(\text{H}_2\text{O}\)), so place a coefficient of \(2\) in front of \(\text{HCl}\).

Final balanced equation: \[ 1\ \text{Na}_2\text{S}_2\text{O}_3 + 2\ \text{HCl} \rightarrow 1\ \text{S} + 1\ \text{SO}_2 + 2\ \text{NaCl} + 1\ \text{H}_2\text{O} \]

Sum of coefficients: \[ 1 + 2 + 1 + 1 + 2 + 1 = 8 \]

✅ Answer: (C)

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