How many known elements have atoms, in their ground-state, with valence electrons whose quantum numbers are n = 5 and l = 1?a. 3

(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).

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redox reactions

The formula for molality is

Given: A solution's molality equals 2.25 m
The weight of the solvent is 30 g, which is the same as 0.030 kg
Molecular weight of AlCl3 is 133.34 g/mol

Thus, we have the equation, 2.25 =
Therefore, the weight of the solute (g) becomes 9.00 g

Hence, <span>9.00 g of AlCl3 is necessary for creating a 2.25m solution in 30.0 g of water</span>

Halogens are characterized as a group of 7 on the periodic table. Each of these elements has 7 valence electrons, needing just one additional electron to fill their outer shell, resulting in their high reactivity. Moreover, the periodic law indicates that when the elements are arranged by increasing atomic number, similar patterns in their properties emerge. Thus, halogens exhibit comparable behaviors during chemical reactions with one another, which is indeed accurate.