IGCSE Chemistry: Specimen Questions with Answers 207 - 209 of 240

Question number: 207

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Water reacts with sodium. The products are sodium hydroxide and hydrogen. Write a word equation for this reaction

Explanation

Sodium metal reacts rapidly with water to form a colourless solution of sodium hydroxide and hydrogen gas . The reaction is exothermic. The reaction is given below.

 Image Exothermic A

Image Exothermic A

Image Exothermic A

 Image Exothermic D

Image Exothermic D

Image Exothermic D

 Image Exothermic C

Image Exothermic C

Image Exothermic C

 Image Exothermic B

Image Exothermic B

Image Exothermic B

Question number: 208

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Question

Pickles can be used for months because it’s manufactured through a process called ‘pickling’. In the process we use an ingredient which is a mild solution of acetic acid.

The name of the ingredient is ________.

Choices

Choice (4) Response

a.

Vinegar

b.

Hydrochloric acid

c.

Nitric acid

d.

Sulphuric acid

Answer

a.

Explanation

Vinegar can kill bacterias as it’s of acidic nature.

Vinegar is dilute solution of acetic acid . Because of being an acid Vinegar is mainly used as a cooking ingredient, or in pickling. As the most easily manufactured mild acid, it has historically had a great variety of industrial, medical, and domestic uses, some of which (such as its use as a general household cleaner) are still commonly practiced today.

Question number: 209

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Substances can be classified as:

Elements can be divided into:

  1. Define each of the following terms:

mixture

[1 Marks]

Explanation

a compound is a substance that results from a combination of two or more different chemical element s, in such a way that the atom s of the different elements are held together by chemical bonds that are difficult to break.