Exam

Question 1

Decomposition

Answer 1

When one complex compound breaks down to two or more simpler compounds. Eg. NH4NO3 -> N2O + H2O

Question 2

Synthesis

Answer 2

Reaction in which two or more simpler substances (elements) combine chemically to give a compound. Eg. 2H2 + O2 -> 2H2O

Question 3

Substitution (single replacement)

Answer 3

A single free element replaces or is substituted for one of the elements in the compound. Eg. 2K + 2H2O -> 2KOH + H2

Question 4

Precipitation (double replacement)

Answer 4

When part of two ionic compounds are exchanged making two new compounds. Eg. BaCl2 + NaSO4 -> BaSO4 + 2NaCl

Question 5

Neutralisation

Answer 5

Reaction between an acid and a base. A salt and water are the products. Eg. H2SO4 + CaCO3 -> CaSO4 + H2O + CO2

Question 6

Redox

Answer 6

Reaction in which electron transfer occurs. Eg. 2Na + Cl2 -> 2NaCl

Question 7

Combustion

Answer 7

Chemical reactions in which a substance reacts with oxygen and heat is released. Eg. Fuel + O2 -> H2O + CO2

Question 8

What are some examples of reactions at home that you speed up?

Answer 8

Frying an egg
Baking a cake
Caramelisation

Question 9

How does temperature affect the rate of reaction?

Answer 9

Heating makes particles in the reactants move faster and collide more often.

Question 10

How does surface area affect the rate of a reaction?

Answer 10

The greater number of exposed particles, the frequency of collisions increases.

Question 11

How does a catalyst affect the rate of reaction?

Answer 11

Lower energy required for a reaction to occur.

Question 12

How does the amount or concentration affect the rate of reaction?

Answer 12

More particles are present which increases the frequency of collisions.

Question 13

Why must particles collide before they can react?

Answer 13

During chemical reactions, particles (atoms, molecules or ions) collide and are rearranged to produce new particles. The collision theory explains why some collisions result in reactions and other do not.

Question 14

What are the key points of the collision theory?

Answer 14

For a reaction to occur, the reactants must:

• collide with each other
• collide with sufficient energy to break bonds within the reactants
• collide with the correct orientation to break the binds within the reactants and so allow the formation of new products.

Question 15

Why are metals malleable and ductile?

Answer 15

Metallic bonds are non-directional and layers of positive ions can simply slip over each other.

Question 16

Why do non-metal atoms share pairs of valence electrons?

Answer 16

The valence electrons of non-metal atoms are eye strongly held. Hence, these electronegative atoms share their electrons and form covalent bonds.

Question 17

Phenotypes

Answer 17

Characteristics that result from the expression of an organism genotype. Phenotype both depends on genotype and the environment.

Question 18

DNA

Answer 18

Abbreviation of deoxyribonucleic acid, it is the chemical substance found in all living things that encodes the genetic information of an organism. DNA is composed of building blocks called nucleotides, which are linked together in a chain.

Question 19

Cell Division

Answer 19

A process that results in the production of new cells.

Question 20

Mitosis

Answer 20

Cell division process that results in genetically identical cells with the same number of chromosomes as the original cell.

Question 21

Meiosis

Answer 21

Cell division process that results in new cells with half the number of chromosomes as the original cell.

Question 22

Genotype

Answer 22

Genetic instructions contained in DNA inherited from parents at a particular gene locus.

Question 23

Somatic Cell

Answer 23

Cells of the body that are not sex cells.

Question 24

Autosomes

Answer 24

Non sex chromosomes.

Question 25

Nucleus

Answer 25

Membrane bound organelle containing the genetic material of DNA.

Question 26

Chromosomes

Answer 26

Tiny thread like structures inside the nucleus of a cell. Chromosomes contain the DNA that carries genetic information.

Question 27

Fertilisation

Answer 27

Penetration of the ova by sperm.

Question 28

Dominant

Answer 28

Refers to a trait (phenotype) that requires only one allele to be present for its expression in a heterozygote.

Question 29

Recessive

Answer 29

Refers to a trait that will only be expressed in the absence of an allele for the dominant trait.

Question 30

Homozygous

Answer 30

Having two identical alleles for a characteristic in the genotype.

Question 31

Heterozygous

Answer 31

Having two different alleles for a characteristic.

Question 32

Allele

Answer 32

Alternative forms a gene for a particular characteristic. Each allele is characterised for a slightly different nucleotide sequence.

Question 33

RNA

Answer 33

Type of nucleic acid and is made up of nucleotides. Ribonucleic acid. RNA contains the sugar ribose and uracil is one of the nitrogenous bases.

Question 34

Gene

Answer 34

Segment of DNA molecule with a coded set of instructions in its base sequence for a specific protein product when expressed may determine the characteristics of an organism.