IB DP Biology A1.1 Water Exam Style Questions HL Paper 1
IB DP Biology A1.1 Water Exam Style Questions HL Paper 1
IB DP Biology A1.1 Water Exam Style Questions HL Paper 1 at IITian Academy focus on a specific topic or type of questions asked in actual exam. Questions are based on new syllabus for first assessment of 2025.
A1.1 Water Topics : Polarity, Hydrogen Bonding, Solvent Properties, Physical Properties, Consequences, Extraterrestrial Life
Question
The mean air and water temperatures recorded at the same time of day at various distances downstream from the city of Asunción on the Lower Paraguay River over an 8-day period shows a relation. What accounts for the differences between the water and air temperatures ?
A. Evaporation of surface water causes an increase in the temperature of surface water.
B. Adhesion between water molecules prevents heat absorption, so its temperature remains lower.
C. Heat is rapidly lost from water due to breakage of covalent bonds.
D. Breakage of hydrogen bonds in water requires much heat energy.
▶️Answer/Explanation
Ans. D
The correct answer is:
D. Breakage of hydrogen bonds in water requires much heat energy.
Explanation:
Water has a high specific heat capacity, meaning it takes a lot of energy to increase its temperature compared to air. This is due to the hydrogen bonds between water molecules, which must be broken for water to warm up. Conversely, when water cools, hydrogen bonds reform and release heat slowly, making water temperature more stable compared to air temperature.
- Option A (Evaporation increases surface water temperature) is incorrect because evaporation removes heat from the surface, leading to cooling rather than warming.
- Option B (Adhesion prevents heat absorption) is incorrect because adhesion affects how water interacts with surfaces but does not prevent heat absorption.
- Option C (Breakage of covalent bonds causes heat loss) is incorrect because covalent bonds in water molecules do not break under normal temperature changes—only hydrogen bonds break and reform.
Thus, the correct explanation for the temperature difference is that hydrogen bonds in water require much heat energy to break, making water temperature change more slowly than air temperature.
Question
Water has a specific heat capacity of \(4.2 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}\) at room temperature, a latent heat of vaporization equal to \(2257 \mathrm{~J} \mathrm{~g}^{-1}\), and a boiling point of \(100{ }^{\circ} \mathrm{C}\). What are the specific heat capacity, latent heat of vaporization and boiling point of methane?
▶️Answer/Explanation
Ans:A
To determine the specific heat capacity, latent heat of vaporization, and boiling point of methane, we need to refer to known physical properties of methane. Here are the values:
1. **Specific Heat Capacity**: The specific heat capacity of methane gas (\(CH_4\)) at room temperature is approximately \(2.2 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}\).
2. **Latent Heat of Vaporization**: The latent heat of vaporization of methane is about \(510 \mathrm{~J} \mathrm{~g}^{-1}\).
3. **Boiling Point**: The boiling point of methane is \(-161.5{ }^{\circ} \mathrm{C}\) (or \(111.65 \mathrm{~K}\)).
These values are significantly different from those of water due to the different molecular structures and intermolecular forces involved. Methane has a much lower boiling point and latent heat of vaporization compared to water, reflecting its weaker intermolecular forces.
Question
Where do hydrogen bonds form?
Between the slight negative charge of hydrogen and slight positive charge of oxygen within a water molecule
Between the slight positive charge of hydrogen and slight negative charge of oxygen within a water molecule
Between the slight positive charge of hydrogen and slight negative charge of oxygen in different water molecules
Between the slight negative charge of hydrogen and slight positive charge of oxygen in different water molecules
▶️Answer/Explanation
Ans: C
Hydrogen bonds form **between the slight positive charge of hydrogen and slight negative charge of oxygen in different water molecules**.
In water, the oxygen atom is more electronegative than the hydrogen atoms, creating a polar molecule where the oxygen has a slight negative charge and the hydrogens have a slight positive charge. Hydrogen bonds occur when the slightly positive hydrogen atom of one water molecule is attracted to the slightly negative oxygen atom of another water molecule. This intermolecular attraction is what gives water many of its unique properties, such as high surface tension and the ability to form droplets.