Question 17:
False; cutting hair would change what it looks like but, braiding it keeps it the same substance it is.
Question 18 :
My best guess would either be A or D. I would lean more towards D because if there are different mixtures then it depends on what you are mixing.
Hope it helps in some way. <3
Answer:

Explanation:
Step 1. Determine the cell potential
<u> E°/V </u>
2×[Cr ⟶ Cr³⁺ + 3e⁻] 0.744 V
<u>3×[Cu²⁺ + 2e⁻ ⟶ Cu] </u> <u>0.3419 V
</u>
2Cr + 3Cu²⁺ ⟶ 3Cu + 2Cr³⁺ 1.086 V
Step 2. Calculate ΔG°

The flat sheet will completely rust before the iron cube. Since they both have the same volume, the flat sheet has more surface area than the small cube. This means more particles are exposed on the flat sheet that can react in a chemical reaction.
They diffuse through small pores at the bottom of the leaf called stomata.
Plants can open and close their stomata, they open them to get water and carbon dioxide in but then close them to ensure the water doesn't 'leak' back out. This is important for plants growing in drier conditions like the cactus.
Answer:
Explanation:
Alkyl groups are those which are derived from alkane by the removal of one hydrogen atom
For example ,methane CH4, and its corresponding alkyl groups is methyl -CH3