expands unevenly between 0 ºC and 4 ºC
maintains fixed density
has low freezing point
wets glass
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You're right! Water does wet glass, which can make it difficult to read measurements in a thermometer. However, the main reason water is not a good thermometric liquid is its anomalous expansion between 0°C and 4°C.
Wetting glass (Option D) is a secondary issue, but it can be overcome by coating the glass with a hydrophobic substance. The irregular expansion (Option A) directly affects the accuracy of temperature readings, making it the primary reason water is unsuitable for thermometers.
Option D, "wets glass," refers to the property of water to adhere to glass surfaces, which is not directly related to its suitability as a thermometric liquid. While this property may have practical implications in certain contexts, it is not a primary factor in determining the suitability of a substance as a thermometric liquid. Therefore, option A, which addresses the thermal expansion properties of water, is the more relevant choice in this context.
Water is not a good thermometric liquid primarily because it A. expands unevenly between $0 \text{ \textdegree C}$ and $4 \text{ \textdegree C}$.
Detailed ExplanationA good thermometric liquid must expand uniformly over the temperature range it measures.1Anomalous Expansion of Water: Water exhibits anomalous expansion.2 Unlike most liquids, which continuously expand as temperature rises, water:Contracts (decreases in volume) as its temperature increases from $0 \text{ \textdegree C}$ to $4 \text{ \textdegree C}$.Reaches its maximum density (minimum volume) at 3$4 \text{ \textdegree C}$.4Expands (increases in volume) only when heated above 5$4 \text{ \textdegree C}$.6Problem for Thermometry: This non-uniform (anomalous) change in volume near its freezing point means that a water thermometer could indicate the same reading for two different temperatures (e.g., $1 \text{ \textdegree C}$ and $7 \text{ \textdegree C}$ if its volume happens to be the same at both). This makes it unreliable for accurate temperature measurement.Why Other Options are Less SignificantD. Wets glass: While water does wet glass (unlike mercury), causing it to stick to the walls of the thermometer tube (leading to errors in reading), the anomalous expansion (A) is the more fundamental and prohibitive characteristic that disqualifies it as a reliable thermometric liquid.C. Has low freezing point: A low freezing point is actually a desirable characteristic for a thermometer, as it allows measurement of low temperatures. Water's freezing point ($0 \text{ \textdegree C}$) is not unusually low compared to common thermometric liquids like mercury (freezing at $-39 \text{ \textdegree C}$) or ethanol (freezing at $-114 \text{ \textdegree C}$).B. Maintains fixed density: This is false, as the entire basis of thermometry is a change in density (or volume) with temperature.
The correct answer is A. Water expands unevenly between 0 ºC and 4 ºC, which makes it unsuitable as a thermometric liquid because it does not provide consistent and reliable measurements across different temperatures.
Baba its not only water that wets glass
alcohol wets glass and by function of that reason tha answer is A
The correct answer is **A. expands unevenly between 0 ºC and 4 ºC**.
Water is not ideal as a thermometric liquid because its density anomaly causes uneven expansion within this temperature range. Between 0°C and 4°C, water actually becomes denser as it warms, which disrupts consistent volume changes needed for accurate temperature readings.
