Select the correct answers and explanations for the following multiple-choice questions: 15. Metals react with acid to liberate......... A. hydrogen gas 16. One of the following cannot be used to cont

Here are the answers to questions 15-19:

15. Metals react with acid to liberate.........

• A. hydrogen gas
• Explanation: When reactive metals react with dilute acids, they displace hydrogen, producing a salt and hydrogen gas. For example, $Mg(s) + 2HCl(aq) \rightarrow MgCl_2(aq) + H_2(g)$.

16. One of the following cannot be used to control food poisoning?

• B. Improper storage and temperature control
• Explanation: Improper storage and temperature control allow harmful bacteria to grow rapidly in food, which is a primary cause of food poisoning. Therefore, it is a practice that leads to food poisoning, not one that controls it.

17. Group VIII elements are .........

• C. unreactive
• Explanation: Group VIII elements (also known as Group 18 or noble gases) have a full outer electron shell, making them chemically stable and unreactive.

18. Which of the following cannot be used to control pollution in Ghana?

• C. Placing liquid and semi-liquid wastes in unlined pits
• Explanation: Placing wastes in unlined pits allows pollutants to seep into the soil and groundwater, causing severe environmental contamination. This practice actively contributes to pollution rather than controlling it.

19. Which of the following practices cannot cause diseases in man?

• B. Eating balanced meals
• Explanation: Eating balanced meals provides essential nutrients, strengthens the immune system, and promotes overall health, thereby preventing diseases rather than causing them.