Page 51 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

3. Name any two coloured salts. State their respective colours also.

Ans. Two coloured salts are :

• Copper sulphate (CuSO )  blue colour.
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• Ferrous sulphate (FeSO )  light green.
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4. Name any two edible acids and the sources from which they are obtained.
Ans. Two edible acids with their sources are :

S. No. Acids Sources

1. Oxalic acid Tomato
2. Malic acid Apple

5. Name any two atoms whose ions exist in more than one type of charged species.

Ans. Two atoms whose ions exist in more than one type of charged species are copper
and iron.

6. What is a universal indicator?

Ans. A universal indicator is composed of a solution of several compounds and it gives
different colours for most of the PH values.

7. Define neutral salts.

Ans. Neutral salts are formed by the neutralisation reaction between strong acids and
strong bases.

F. Short-answer questions

1. What are elements and compounds? Give examples of each.
Ans. Elements : An element is a pure substance made up of only one kind of atoms.

It represents the simplest form of a pure substance that cannot be broken down

into more simpler substances by normal chemical means. For example, gold, silver,
aluminium, hydrogen, oxygen, etc., are all elements.

Compounds : A compound is a pure substance formed by the chemical combination

of two or more elements in a fixed ratio by mass. It is a pure substance made up of

the same kind of molecules. For example, sodium chloride is a compound made up
of elements sodium (Na) and chlorine (Cl). Here, Na and Cl always combine in a fixed

mass ratio to form a molecule of sodium chloride.

2. Differentiate between homogeneous and heterogeneous mixtures. Also, give two
examples in each category.

Ans. Homogeneous Mixtures : These mixtures have a uniform composition throughout.

They do not show separate boundaries of the constituent substances. Homogeneous

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