Which substance is most likely to dissolve in greater quantities in cold water

Explanation:

5.5 billion grains of sand (5.5×10^9 grains)

Assuming the amount of brown sand is 6.0%, how many brown grains are found in the bucket?

Grains of brown sand = Percentage of brown sand * Total sand in the bucket

Calculated brown grains = 0.06 * 5.5×10^9 = 0.33 x 10^9 = 3.3 x 10^8 grains

If the concentration of brown sand is 6.0 ppm, what is the number of brown grains in the bucket?

Grains of brown sand = Concentration of brown sand * Total sand in the bucket

6 ppm = 6 / 1,000,000 = 0.000006

Calculated brown grains = 0.000006 * 5.5×10^9 = 3.3 x 10^4 grains

If the concentration of brown sand is 6.0 ppb, how many brown grains exist in the bucket?

Grains of brown sand = Concentration of brown sand * Total sand in the bucket

6 ppb = 6 / 1,000,000,000 = 0.000000006

Calculated brown grains = 0.000000006 * 5.5×10^9 = 3.3 x 10^1 = 33 grains

(c) Cu + S → CuS is classified as a redox reaction

Explanation:

The following reactions are presented:

(a) K₂CrO₄ + BaCl₂ → BaCrO₄ + 2 KCl

(b) Pb²⁺ + 2 Br⁻ → PbBr₂

(c) Cu + S → CuS

Reaction (c) represents a redox reaction, as the oxidation states of the elements are changing. In this case:

Cu + S → CuS

In its elemental form, Cu has an oxidation state of 0, while in CuS (copper sulfide), its oxidation state changes to +2.

Similarly, S in its elemental form has an oxidation state of 0 and is -2 in CuS (copper sulfide).

Learn more about:

redox reactions