ICSE ICSE Class 7 - CISCE Question Bank Solutions for Chemistry

Fill in the blank

An excess of electrons produces a ________ charge.

Fill in the blank

A deficiency of electrons produces a ________ charge.

Elements X and Y have 1 and 7 electrons in their outermost shell respectively.

Which element will lose electron?

Elements X and Y have 1 and 7 electrons in their outermost shell respectively.

Which element will gain electron?

Elements X and Y have 1 and 7 electrons in their outermost shell respectively.

Which will form positive ion?

Elements X and Y have 1 and 7 electrons in their outermost shell respectively.

Which will form negative ion?

Elements X and Y have 1 and 7 electrons in their outermost shell respectively.

What will be the charge present of the molecule XY after chemical combination?

What is the number of electrons donated by a magnesium atom and number of electrons accepted by a sulphur atom during their chemical combination?

How many units of charge are developed on each atom?

What is the number of electrons after the transfer of electrons in magnesium and sulphur atoms.

Diagrammatically represent the transfer of electrons.

Write the molecular formulae of Magnesium nitride:

State the meaning of the term – (a) atom, (b) molecule, (c) radical – with a suitable example.

Draw the basic structure of an atom representing its –

1. Subatomic particles
2. Nucleus
3. Orbits or shells.

‘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’.

A radical take part – unsplit in a chemical reaction and retains its identity in reactions.
With reference to the radical –

1. ammonium
2. bisulphate
3. carbonate

state the group of atoms present in each radical.

‘Dilute hydrochloric acid is added to sodium hydroxide’. Give a word equation and a molecular equation of the same. Is the equation written, a balanced equation. Give reasons.

Fill in the blank:

A molecule of an element is _________.

Fill in the blank:

The formula of aluminium sulphate is _________.