Expansion — Set 3

Correct Answer: D. 4°C

Water becomes densest at about 4°C due to anomalous expansion. Around this point, its volume is minimum. This behavior affects lake freezing patterns in winter.

Correct Answer: D. Has a low freezing point

Alcohol stays liquid at much lower temperatures than water. So it can measure low temperatures without freezing. It also expands noticeably, giving readable changes in level.

Correct Answer: A. Invar

Invar is designed to expand very little with temperature. Its linear expansion coefficient is much smaller than most common metals. That is why it is chosen for precision length standards.

Correct Answer: B. Lower expansion coefficient

The metal with higher expansion tries to become longer. This forces the combined strip to curve with the higher-expansion side on the outer arc. So the strip bends toward the metal with lower expansion coefficient.

Correct Answer: D. Apparent = Real − Container expansion

Real expansion is the true increase in liquid volume. The container’s expansion increases the space available inside it. So apparent expansion equals real expansion minus container expansion.

Correct Answer: D. Contracts on heating from 0°C to 4°C

Most liquids expand when heated, but water behaves differently near 0°C. From 0°C to 4°C, heating causes water to contract. This is why density increases up to about 4°C.

Correct Answer: C. 3 : 2 : 1

In isotropic solids, β is about 2α and γ is about 3α. So the ratio γ:β:α becomes 3:2:1. This approximation is used for small temperature changes.

Correct Answer: A. Numerically the same

A temperature interval of 1°C equals 1 K. Expansion coefficients depend on temperature difference, not absolute zero point. So their numerical values per °C and per K are the same.

Correct Answer: D. Allow thermal expansion and contraction

Bridges expand in hot weather and contract in cold weather. Without joints, thermal stress could crack or warp the structure. Expansion joints provide room for safe movement.

Correct Answer: B. Mass

Heating changes dimensions because of thermal expansion. It does not add or remove material from the rod. So the mass remains essentially unchanged while length and volume increase.