Most sidewalks are made out of solid concrete sections. There are spaces between the sections. What happens to the spaces during a hot day in the summer and why?

The options are :

The spaces get wider because the concrete sections shrink.

The spaces stay the same because the concrete sections does not shrink or expand.

The spaces get narrower because the concrete sections expand.

Some spaces get wider, some spaces get narrower, and some spaces stay the same because each concrete section behaves differently on a hot summer day.

The answer is

Some spaces get wider, some spaces get narrower, and some spaces stay the same because each concrete section behaves differently on a hot summer day.

Concrete surfaces react with a change in temperature by either shrinking or expanding depending on the temperature difference.

When there is an increase in temperature it expands a bit and shrinks a bit too when the temperature is decreased.

c. heat from the poles back down towards the equator.

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation: