CHEMISTRY

Question 1

How will temperature affect the pressure of a fixed volume of gas

Answer 1

Higher pressure leads to higher kinetic energy and increased pressure

Question 2

What is diffusion

Answer 2

net movement of particles from high concentration to low concentration

Question 3

whats an element

Answer 3

contains only 1 type of atom and cannot be split by any chemical means

Question 4

whats a compound

Answer 4

two or more elemnts chemically combined and cannot be seperated

Question 5

whats a mixture

Answer 5

contains 2 or more elements not chemically combined

Question 6

whats a molecule

Answer 6

two or more atoms bonded together

Question 7

whats inside the nucleus

Answer 7

protons and neutrons

Question 8

Whats the charge and mass of protons, neutrons and electrons

Answer 8

protons- + has a mass of 1
neutrons- has no charge and has a mass of 1
electrons- — has a mass of 1/2000

Question 9

how to identify the mass number

Answer 9

the larger number

Question 10

how to identify the atomic number and what do we use it for

Answer 10

the smaller one and we use it to draw the electronic configuration

Question 11

What are isotopes

Answer 11

atoms with the same atomic number but different mass number

Question 12

Give one medical use of radioactive isotopes

Answer 12

treat cancer radiotherapy

Question 13

give one industrial use of radioactive isotopes

Answer 13

tracers to monitor fluid flow and and filtration tracer technique

Question 14

What are the charges in metals and non metals

Answer 14

metals- positive
non-metals- negative

Question 15

why do ionic structures have such high melting and boiling points

Answer 15

they have strong electrostatic forces of attraction

Question 16

Describe the structure of silicon (Iv) oxide ( silicon dioxide )

Answer 16

Each silicon is atom bonds covalently with 4 oxygen atoms
and they have a giant structure

Question 17

Find the Mr of Ca(0H)2

Answer 17

40+(162)+(12)
= 74

Question 18

Find the mass of moles in 5.4g of CacO3

Answer 18

moles=mass/Mr
= 5.4/(40+12+16)
=5,4/100
= 0,054

Question 19

State the major use of this isotope uranium

Answer 19

used in nuclear reactors to generate electricity through fission

Question 20

state the meaning of the term diatomic

Answer 20

a molecule that is made up of two atoms of either the same or different elements

Question 21

state one physical property of an ionic compound

Answer 21

They have strong bonds

Question 22

state the general name given to any positive ion

Answer 22

cation

Question 23

state the percentage of nitrogen in clean dry air.

Answer 23

78

Question 24

state the percentage of oxygen in clean dry air

Answer 24

20.95 percent

Question 25

state the percentage of carbon dioxide in clean dry air

Answer 25

0.04 percent

Question 26

graphite is used as an electrode state another use of graphite

Answer 26

graphite is also a common lubricant

Question 27

statement that describes the structure and bonding in graphite.

Answer 27

Giant covalent

Question 28

State the typical conditions and name the catalyst used in the industrial production of ammonia.

Answer 28

temperature- 450 degrees pressure - 280atm catalyst used- iron

Question 29

Name NH4CL

Answer 29

ammonia chloride

Question 30

hydrochloric acid reacts with iron complete the word equation

Answer 30

Hydrochloric acid + Iron → Iron(II) chloride + Hydrogen

Question 31

State why these isotopes have identical chemical properties.

Answer 31

becasue they have the same number of electrons in the outermost shell.

Question 32

State the name of the amount of substance which contains 6.02*10 23

Answer 32

the mole

Question 33

state why molten MgS conducts electricity

Answer 33

Molten MgS conducts electricity because the ions are free to move and carry charge.

Question 34

State one difference between boiling and evaporation

Answer 34

boiling occurs throughout the entire liquid at a specific temperature (the boiling point), whereas evaporation happens only at the surface of the liquid and can occur at any temperature.

Question 35

State three properties which silicon (III) oxide and diamond have in common.

Answer 35

Have very high melting point Very hard due to giant covalent structure they are insoluble in water

Question 36

How could you show that silicon (IV) oxide is acidic and not basic or amphoteric

Answer 36

Silicon (IV) oxide (SiO₂) reacts with a base like sodium hydroxide to form a salt and water, showing it is acidic.

Question 37

A compound X contains 55.85% carbon, 6.97% hydrogen and 37.18% oxygen how does this prove that compound X contains only carbon, hydrogen and oxygen?

Answer 37

All the percentages add up to 100%, meaning no other elements are present

Question 38

Use the periodic table to calculate the molecular mass of one mole of Al2O3

Answer 38

102

Question 39

Calculate the mass of calcium ions in 200cm3 of his sample of sea water given; 400cm3 mass of ion in 1000cm3

Answer 39

80

Question 40

state what VII refers to in the name potassium manganate

Answer 40

The valency