TCEQ Class C Water License Exam
Questions and Answers | Latest Version
| 2025/2026 | Correct & Verified
What is the chemical formula for chlorine gas?
✔✔Cl₂
What is the typical pH range for safe drinking water?
✔✔6.5 to 8.5
Which chemical is commonly used to raise the pH of acidic water?
✔✔Lime (Ca(OH)₂)
What does alkalinity in water represent?
✔✔The water’s ability to neutralize acids
What is the chemical symbol for calcium?
✔✔Ca
1
,Which compound is commonly used to soften hard water?
✔✔Sodium carbonate (Na₂CO₃)
What gas is released when chlorine reacts with ammonia in water?
✔✔Chloramines
What is the chemical formula for ozone?
✔✔O₃
Which chemical is used as the primary disinfectant in most water systems?
✔✔Chlorine
What does turbidity in water indicate?
✔✔Presence of suspended particles
What ion causes scaling in pipes and equipment?
✔✔Calcium (Ca²⁺)
2
,Which chemical lowers water pH when added?
✔✔Carbon dioxide (CO₂)
What does “free chlorine” mean in water treatment?
✔✔Chlorine available for disinfection after reacting with demand
What is the chemical formula for carbon dioxide?
✔✔CO₂
Which ion is measured in a hardness test along with calcium?
✔✔Magnesium (Mg²⁺)
What chemical is often added to prevent corrosion in water pipes?
✔✔Phosphates
What is the pH of pure water at 25°C?
✔✔7
3
, Which chemical is commonly used to remove iron and manganese from water?
✔✔Potassium permanganate (KMnO₄)
What is the chemical symbol for sodium?
✔✔Na
What does the term “chlorine demand” mean?
✔✔The amount of chlorine consumed before a residual is achieved
Which form of chlorine is most effective at low pH?
✔✔Hypochlorous acid (HOCl)
What chemical is used in jar testing to coagulate particles?
✔✔Alum (Al₂(SO₄)₃)
What does pH measure?
✔✔The concentration of hydrogen ions (H⁺)
4
Questions and Answers | Latest Version
| 2025/2026 | Correct & Verified
What is the chemical formula for chlorine gas?
✔✔Cl₂
What is the typical pH range for safe drinking water?
✔✔6.5 to 8.5
Which chemical is commonly used to raise the pH of acidic water?
✔✔Lime (Ca(OH)₂)
What does alkalinity in water represent?
✔✔The water’s ability to neutralize acids
What is the chemical symbol for calcium?
✔✔Ca
1
,Which compound is commonly used to soften hard water?
✔✔Sodium carbonate (Na₂CO₃)
What gas is released when chlorine reacts with ammonia in water?
✔✔Chloramines
What is the chemical formula for ozone?
✔✔O₃
Which chemical is used as the primary disinfectant in most water systems?
✔✔Chlorine
What does turbidity in water indicate?
✔✔Presence of suspended particles
What ion causes scaling in pipes and equipment?
✔✔Calcium (Ca²⁺)
2
,Which chemical lowers water pH when added?
✔✔Carbon dioxide (CO₂)
What does “free chlorine” mean in water treatment?
✔✔Chlorine available for disinfection after reacting with demand
What is the chemical formula for carbon dioxide?
✔✔CO₂
Which ion is measured in a hardness test along with calcium?
✔✔Magnesium (Mg²⁺)
What chemical is often added to prevent corrosion in water pipes?
✔✔Phosphates
What is the pH of pure water at 25°C?
✔✔7
3
, Which chemical is commonly used to remove iron and manganese from water?
✔✔Potassium permanganate (KMnO₄)
What is the chemical symbol for sodium?
✔✔Na
What does the term “chlorine demand” mean?
✔✔The amount of chlorine consumed before a residual is achieved
Which form of chlorine is most effective at low pH?
✔✔Hypochlorous acid (HOCl)
What chemical is used in jar testing to coagulate particles?
✔✔Alum (Al₂(SO₄)₃)
What does pH measure?
✔✔The concentration of hydrogen ions (H⁺)
4
