ICSE ICSE Class 7 - CISCE Question Bank Solutions for Chemistry

Give the basic demarkation of the Modern Periodic Table into metals, metalloids and non-metals with special reference to halogens and noble gases.

Give a reason why the non-metals – halogens and noble gases are placed in separate groups of the periodic table with special reference to their difference in properties.

State what are metalloids.

Name the elements recognised as metalloids.

Compare the properties of metalloids with those of metals.

State the uses of three different metalloids.

State a specific reason for using steel in automobiles.

State a specific reason for using gold in jewellery

State whether the statement given below is true or false. If false write the correct statement.

Silicon is an example of a metalloid.

Give reasons for the following:

patients suffering from lung problems are kept in an oxygen tent.

Give reasons for the following:

oxygens finds utility in welding & cutting of metals.

Give reason for the following:

Oxygen gas does not affect moist blue litmus paper, but carbon dioxide turns it slightly pink.

Give reason for the following:

Oxidation of sulphur results in a product which turns moist blue litmus red.

State the main points of the contradiction of Dalton’s atomic theory by the Modern Atomic Theory.

‘Atoms of the same element or different from Dalton’s atomic theory by the Modern Atomic Theory.
Give two examples each of –

• Atoms of the same element
• Atoms of different elements combining to form a molecule.

Explain the term ‘atomicity’.

Give a reason why –

Helium is considered monoatomic, but hydrogen a diatomic molecule.

Give a reason why –

Ozone is considered triatomic, but phosphorus a tetratomic molecule.

State the atomicity of the following:

Neon

State the atomicity of the following:

Oxygen