Space shuttle tiles, sandstone, and the glass in quartz halogen lamps are all made out of the same stuff: silicon dioxide. why do the three materials have such different properties?

Explained

Explanation:

The bond angle between the Si-O-Si is 145° .But this can also vary between 100° and 170°,  It is because of which the changes in properties is happening. Bond angles can affect the hybridization, lone pair repulsion and electronegativity.

Thus , Space shuttle tiles, sandstone, and the glass in quartz have different properties and are used according to their property.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.