IB DP Chemistry -Structure 1.1 Introduction to the particulate nature of matters- IB Style Questions For SL Paper 1A -FA 2025
▶️ Answer/Explanation
A mixture of liquid hydrocarbons is typically a uniform, single-phase mixture, making it homogeneous. The most effective method to separate liquids with different boiling points is distillation.
✅ Answer: (A)
▶️ Answer/Explanation
Let the balanced equation be
\( a\,\text{C}_{3}\text{H}_{5}\text{N}_{3}\text{O}_{9}(l) \rightarrow b\,\text{CO}_{2}(g) + c\,\text{H}_{2}\text{O}(l) + d\,\text{N}_{2}(g) + e\,\text{O}_{2}(g) \).
Matching atoms:
Carbon: \( 3a = b \Rightarrow b = 3a \).
Hydrogen: \( 5a = 2c \Rightarrow c = \tfrac{5a}{2} \) (so \( a \) must be even).
Nitrogen: \( 3a = 2d \Rightarrow d = \tfrac{3a}{2} \) (so \( a \) must be a multiple of \( 2 \)).
Choose the smallest such \( a = 4 \). Then
\( b = 12,\; c = 10,\; d = 6 \).
Oxygen check gives \( e = 1 \), so
\( 4\text{C}_{3}\text{H}_{5}\text{N}_{3}\text{O}_{9}(l) \rightarrow 12\text{CO}_{2}(g) + 10\text{H}_{2}\text{O}(l) + 6\text{N}_{2}(g) + \text{O}_{2}(g) \).
Therefore, the coefficient of \( \text{C}_{3}\text{H}_{5}\text{N}_{3}\text{O}_{9}(l) \) is \( 4 \).
✅ Answer: (B)
▶️ Answer/Explanation
Set up the reaction:
\( a\,\text{Ca}_{3}(\text{PO}_{4})_{2} + b\,\text{H}_{2}\text{SO}_{4} \rightarrow c\,\text{CaSO}_{4} + d\,\text{H}_{3}\text{PO}_{4} \)
Balance atoms:
• Calcium: \( 3a = c \Rightarrow c = 3a \)
• Phosphorus: \( 2a = d \Rightarrow d = 2a \)
• Sulfate: \( b = c = 3a \)
Choose smallest \( a = 1 \):
\( b = 3,\; c = 3,\; d = 2 \)
Final balanced equation:
\( \text{Ca}_{3}(\text{PO}_{4})_{2} + 3\text{H}_{2}\text{SO}_{4} \rightarrow 3\text{CaSO}_{4} + 2\text{H}_{3}\text{PO}_{4} \)
Coefficients:
\( \text{H}_{2}\text{SO}_{4}(aq) = 3 \)
\( \text{H}_{3}\text{PO}_{4}(aq) = 2 \)
✅ Answer: D