D NACL because it is ionic bond and all the others are covalent
Answer:
Two, KCl and PbCl₂.
Explanation:
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In this case, since the addition of chloride ions promote the following three ionic reactions:

We can infer that both silver chloride and lead (II) chloride are precipitated products as their Ksp are 6.56x10⁻⁴ and 1.59x10⁻⁵ respectively, which means they are merely soluble in water.
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Most acidic: solution B, pH = 1
Most Basic: solution C, pH = 13
Least acidic: solution A, pOH = 1
Answer:
17)A. Solids
18) A. Frequently collide with each other and with surface of ballon
19) D. Particles are smaller at lower pressure.