Q1. Name the smallest particle that has all the properties of an element.

Ans. Atom.

Q2. How many ions are present in one mole of ions?

Ans. 6.022 x \({10}^{23}\).

Q3. Write the names of symbols of elements where the symbols are taken from their names in English.

Ans. The symbols of the following elements have been taken from their names in English: Calcium (Ca), oxygen (0), zinc (Zn), magnesium (Mg) etc.

Q4. What is an atom according to Dalton’s atomic theory?

Ans. According to Dalton’s atomic theory, an atom is the ultimate particle of matter which cannot be further divided into anything simpler than itself.

Q5. Carbon dioxide, collected from different sources contains carbon and oxygen in the same proportion. Which law of chemical combination governs this?

Ans. This is governed by law of constant proportions.

Q6. Give the chemical names and chemical formulae for the following compounds having common names:

Baking soda, washing soda, blue vitriol, green vitriol, gypsum, oil of vitriol or white vitriol, soda ash, marble, lime water


Common name

Chemical name

Chemical formula

Baking soda

Sodium bicarbonate

\(NaHC{ O }_{ 3 }\)

Washing soda

Sodium carbonate

\(N{ a }_{ 2 }C{ O }_{ 3 }.10{ H }_{ 2 }O\)

Blue vitriol

Copper sulphate

\(CuS{ O }_{ 4 }.5{ H }_{ 2 }O\)

Green vitriol

Ferrous sulphate

\(FeS{ O }_{ 4 }.7{ H }_{ 2 }O\)


Calcium sulphate

\(CaS{ O }_{ 4 }.2{ H }_{ 2 }O\)

Oil of vitriol

Sulphuric acid

\({ H }_{ 2 }S{ O }_{ 4 }\)

Soda ash

Sodium carbonate

\(N{ a }_{ 2 }C{ O }_{ 3 }\)


Calcium carbonate

\(CaC{ O }_{ 3 }\)

Lime water

Calcium hydroxide

\(Ca({ OH) }_{ 2 }\)