Chemistry (Exam Questions)

Question 1

Comment on the chemical properties that each isotope shows:
C-12, C-13, C-14

Answer 1

Same. Same electronic configuration and only that affects chemical properties.

Question 2

How would you expect the element N-14 to compare with C-14 in terms of chemical properties and why?

Answer 2

Different chemical properties. Different number of protons, so different elements.

Question 3

Chadwick’s experimental work on the atom led to a better understanding of isotopes.
Explain how his work led to this understanding.

Answer 3

Chadwick provided evidence to show the existence of neutrons. This was necessary because isotopes have the same atomic number but with different numbers of neutrons.

Question 4

Molecule

Answer 4

When NON-METAL atoms join together, the group of combined atoms is called a molecule.
Molecules may contain atoms of the same type or of different types.
* When molecules contain atoms of the same type – these are molecules of an element.
* When molecules contain atoms of different type – these are molecules of a compound.

Question 5

When don’t diatomic elements have to be in pairs?
E.g. Oxygen is diatomic, but water (H2O) only has one oxygen atom

Answer 5

When they are chemically combined with another element.
It will only be diatomic when on its own.

Question 6

What piece of equipment separates two immiscible liquids? And how?

Answer 6

A separating funnel is used.
e.g. Oil and water are separated simply by running off the more dense liquid (water) by opening
the tap.

Question 7

What will happen if a substance is more strongly attracted to the solvent than the paper?

Answer 7

It will move a long way up the paper with the solvent.

Question 8

What will happen if a substance is more strongly attracted to the paper than the solvent?

Answer 8

It will travel a short distance up the chromatography paper.

Question 9

Why must the starting line be drawn in pencil?

Answer 9

So that it does not dissolve in solvent.

Question 10

Why must the level of solvent in the beaker be below the level of the spots?

Answer 10

So that the spots do not just dissolve into the solution in the beaker.

Question 11

Seawater can be changed into potable water by desalination.
Name the substance removed from seawater by desalination.

Answer 11

Sodium chloride / salt.

Question 12

Give the test and result of chlorine being present

Answer 12

Test: Damp blue litmus
Result: (Turns red) Then is bleached white

Question 13

Desalination

Answer 13

The process of removing salt from sea water