CIE Chemistry (US-0439): Specimen Questions with Answers 208 - 210 of 240

Question number: 208

MCQ▾

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.

Nitric acid

b.

Sulphuric acid

c.

Vinegar

d.

Hydrochloric acid

Answer

c.

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

Short Answer Question▾

Write in Short

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.

Question number: 210

Short Answer Question▾

Write in Short

One of the factors which determine the reaction rate of solids is particle size.

  1. A mixture of finely powdered aluminum and air may explode when ignited.

    An explosion is a very fast exothermic reaction. This causes a large and sudden increase in temperature.

    Explain each of the following in terms of collisions between reacting particles.

Explain why for most reactions the rate of reaction decreases with time.

Explanation

The rate of a chemical reaction is dependent on the concentration of the reagents. … The reason we care about this is that over the course of a reaction the concentration of the reagents decreases. This is because the reagents, over time, are getting used up in order to make the products.