Adires srade 11 (1) following: (1) (a) Agricuttural industry (1) (b) Household use. 2,2.4 Indicate the chemical formula of compound \( A \). (1) 2.2.5 Supply the scientific name of the compound labelled \( B \) after the bonding is complated. 2.2.6 Determine the number of valence electrons for each of the two atoms in diagram B. (2) 2.3 Draw the Lewis structure of the following atoms: (1) 2.5.1 Hydrogen. (1) 2.5.2 Calcium (1) 2.4.1 Name the building blocks of a protein molecule. (2) 2.4.2 Distinguish between essential and non-essential amino acids. (3) 2.4.3 Give THREE importance of proteins in an animal diet. (6) 2.5.1 Classify the following substances as acids or bases. Hydrochloric acid, Ammonia, Milk, Vinegar, Lemon juice, Baking soda 2.5.2 The PH scale ranges from (a) .... to (b) ..... with the strongest base having a PH of (c) ....... (3) (35)

**2.2.4. Indicate the chemical formula of compound \(A\).** Assuming that compound \(A\) is the one used in the agricultural industry (for example, as a fertilizer), a common choice is ammonium nitrate. Its chemical formula is \[ \mathrm{NH_4NO_3} \] **2.2.5. Supply the scientific name of the compound labelled \(B\) after the bonding is completed.** For a compound used in household applications, a common example is table salt. Its scientific name is \[ \text{sodium chloride} \] **2.2.6. Determine the number of valence electrons for each of the two atoms in diagram \(B\).** In sodium chloride the bonding occurs between a sodium atom and a chlorine atom: - A sodium atom has \(1\) valence electron. - A chlorine atom has \(7\) valence electrons. **2.5.1. Draw the Lewis structure of the following atoms:** 1. *Hydrogen:* The hydrogen atom has one electron. Its Lewis structure is represented as \[ \mathrm{H\cdot} \] 2. *Calcium:* A calcium atom has two electrons in its outermost shell (its electron configuration places the valence electrons in the \(4s\) orbital). Its Lewis structure is represented as \[ \mathrm{Ca:} \quad \cdot\cdot \] (Here the two dots indicate the \(2\) valence electrons.) **2.4.1. Name the building blocks of a protein molecule.** The building blocks of proteins are \[ \textbf{amino acids.} \] **2.4.2. Distinguish between essential and non‐essential amino acids.** - \(\textbf{Essential amino acids}\): These cannot be synthesized by the body and must be obtained from the diet. - \(\textbf{Non-essential amino acids}\): These can be synthesized by the body even if they are not supplied directly by the diet. **2.4.3. Give THREE importance of proteins in an animal diet.** 1. They provide the essential amino acids required for growth and tissue repair. 2. They function as enzymes, hormones, and antibodies that regulate vital body processes. 3. They help maintain fluid balance and support immune system function. **2.5.1. Classify the following substances as acids or bases.** - **Hydrochloric acid:** Acid - **Ammonia:** Base - **Milk:** Slightly acidic (in general, milk has a pH around 6.7–6.9, so it is considered mildly acidic) - **Vinegar:** Acid - **Lemon juice:** Acid - **Baking soda:** Base **2.5.2. The pH scale ranges from (a) .... to (b) ..... with the strongest base having a pH of (c) ....** \[ \text{(a) } 0,\quad \text{(b) } 14,\quad \text{(c