Among the following solids, the lowest co-efficient of expansion is forA     ConcreteB     Rubber C     GlassD     silicon

The coefficient of thermal expansion refers to the change in size of a material with a change in temperature. Different materials have different coefficients of thermal expansion.

Here is a step-by-step guide to answering the question:

Step 1: Understand the question. The question is asking which of the given materials - concrete, rubber, glass, or silicon - has the lowest coefficient of thermal expansion.

Step 2: Research or recall the coefficients of thermal expansion for the given materials.

Step 3: Compare the coefficients of thermal expansion for the given materials.

Step 4: Identify the material with the lowest coefficient of thermal expansion.

Based on general knowledge and data, silicon has the lowest coefficient of thermal expansion among the given options. Therefore, the answer is D. Silicon.