IGCSE Chemistry: Specimen Questions with Answers 115 - 117 of 240

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Question 115

Question

MCQ▾

Which among the following is not a physical process in the treatment of industrial wastes?

Choices

Choice (4)

a.

Filtration

b.

Floatation

c.

Sedimentation

d.

Precipitation

Answer

d.

Explanation

Precipitation is a chemical process and not a physical process in the treatment of industrial wastes.

Question 116

Edit

Write in Short

Short Answer▾

Explain why iodine does not react with potassium bromide. [Total: 10 Marks]

Explanation

Iodine does not react with potassium bromide because the less reactive element is removed from the compound and replaced by the more reactive element. For example, if iodine is added to a solution of potassium bromide, then there is no reaction.

Question 117

Question

MCQ▾

According to “Vitalism theory” :

Choices

Choice (4)

a.

Vitamins are organic substances.

b.

Vital force is responsible for the preparation of inorganic substances.

c.

Vitamins are inorganic substances.

d.

Vital force is responsible for the preparation of organic substances.

Answer

d.

Explanation

  • According to “Vitalism theory” , the organic substances in nature are directly derived from the nature. They cannot be prepared artificially. There is some natural force which prepares these organic substances. This force was known as vital force.
  • Thus according to “Vitalism theory” , vital force is responsible for the preparation of organic substances. Organic substances such as urea, methane, chloroform, etc. cannot be prepared in the laboratory. Today this theory is invalid because thousands of organic compounds are being prepared in the laboratory.

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