Class 8 General Science Notes: - Unit-7: Acid, Base and Salt : Solved Exercise (Short Questions and Answers)
(National Book Foundation - New Book/New Syllabus Based on National Curriculum Pakistan 2023-2024 and Onwards)
(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)
(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)
B. Short Questions
B. Short Questions
i). You cannot neutralize the effects of wasp sting with calcium hydroxide? Give reason.
Ans:When a wasp stings, it injects an alkali into the skin. This causes burning, pain, and swelling on the skin. Its effect can be neutralized by rubbing an acid like vinegar on it, whereas calcium hydroxide is an alkali and it cannot neutralize the effect of a wasp sting.
ii). You can neutralize the effects of bee stings with calcium hydroxide. Give reason.
Ans:
When an ant or bee stings, it injects an acid under the skin. It can be neutralized by rubbing baking soda or calcium hydroxide on it because these are alkalis.
iii). Antacids are used to treat indigestion. Justify.
Ans:
Antacids contain alkalis such as magnesium hydroxide also known as milk of magnesia. During indigestion, taking milk of magnesia gives relief, since it neutralizes the effect of excess acid.
iv). Which acid and base would you use to make potassium chloride?
Ans:
Potassium chloride ions come from strong acid (HCl) and strong base (KOH).
iv). Toothpaste is made slightly alkaline. Justify.
Ans:
Toothpaste contains an alkali, so brushing toothpaste neutralizes acid and prevents tooth decay.
iv). Which of the following solutions will have a pH of more than 7.
1. Milk of magnesia 2. Drain cleaner 3. Vinegar
Ans:
Milk of magnesia and Drain cleaner has a PH of more than 7.
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Unit-7: Acid, Base and Salt: Solved Short Questions and Answers
Source: General Science Book (National Book Foundation, Pakistan)
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