science

Question 1

Distinguish between the terms-atoms and ions

Answer 1

Atoms is the smallest building block of life, whereas ions are charged atoms that have either gained anions or lost cations electrons.

Question 2

Cations vs Anions?

Answer 2

Cations: is pawsitive as it loses electrons
Anions: is negative as it gained electrons

Question 3

Element vs compound?

Answer 3

Elements: consist of one type of atom. E.g: oxygen and fluorine
Compound: consists of two or more types of atoms. E.g: sodium chloride( made up of sodium and chloride).

Question 4

How is the modern periodic table organised

Answer 4

They are arranged in increasing atomic number(number of protons)
Groups: vertical column(1-18 or I - VII)
Periods are the horizontal rows(1-7)

Question 5

what is ionic and covalent substances and provide two examples of each.

Answer 5

Ionic compounds are formed when metal and non-metal atoms chemically bond and one atom transfers electrons from one to the other. Examples are sodium fluoride and Aluminum oxide.
Covalent compounds form through two non-metals chemically bonded when atoms share electrons to achieve a full outer electron shell. Eg: h2o and carbon dioxide

Question 6

what is physical change and provide examples

Answer 6

Physical change: is changing the product appearance or state of a substance without changing its chemical identity. Example: ice melting, sugar dissolving in water.

Question 7

what is chemical change, provide examples and indicator of chemical change:

Answer 7

Chemical changes are irreversible change and new substances are formed. Eg: burning wood, or baking a cake. Indicator of Chemical change:
- light produced
-heat absorb/produced
-gas produced(bubbles)
-precipitate formed.
-change in colour.
- shell produced.

Question 8

What is the law of conservation of mass?

Answer 8

The law of conservation of mass states that matter cannot be created nor destroyed, but rearranged to form new substances.

Question 9

What is the general word equation for a chemical reaction

Answer 9

reactants → products.

Question 10

Types of chemical reactions:

Answer 10

Synthesis(making): A compound is made from simpler materials.Eg: A + B = AB(opposite of decomposition)
Decomposition: A compound is broken down into simpler compounds, or down into the element they make it up(opposite of synthesis)

Question 11

Define precipitate:

Answer 11

A precipitate is a solid that forms and separates from a liquid solution during a chemical reaction. This occurs when two dissolved substances react together to form an insoluble product, which then “precipitates” out of the solution. Eg: Two clear salt solutions mix to form an insoluble solid.

Question 11

SNAAP, soluble in water:

Answer 11

S = Sodium (Na⁺)
N = Nitrates (NO₃⁻)
A = Ammonium (NH₄⁺)
A = Acetates (CH₃COO⁻)
P = Potassium (K⁺)

Question 12

States of matter:

Answer 12

(s): Solid (not dissolved or is a precipitate).
(l): Liquid (used for pure liquids like water, mercury, ethanol).
(g): Gas (gaseous substances like CO₂, O₂).
(aq): Aqueous (dissolved in water).

Question 13

what is complete combustion and provide general equation:

Answer 13

When the fuel has a sufficient amount of oxygen, it reacts fully with oxygen, producing carbon dioxide(Co2)and water(h2o) as the primary products.
General equation: Fuel (hydrocarbon)(g)+O2​(g)⟶CO2​(g)+H2​O(g/l).

Question 14

What is incomplete combustion and provide general equation:

Answer 14

When the fuel has an insufficient amount of oxygen, the fuel reacts fully with oxygen which results in the formation of other products like carbon monoxide (CO), carbon (soot), or even partially oxidized hydrocarbons, along with water.
General equation:Fuel (hydrocarbon)(g)+O2​(g)⟶CO(g)+H2​O(g/l).

Question 15

What occurs during the neutralization reactions:

Answer 15

A reaction happens between acid and base which forms salt and water.

Question 16

what is the highest point of the waves called?

Answer 16

the crest

Question 17

what is the lowest point of the waves called?

Answer 17

the trough

Question 18

what is the height of the wave to the crest or the trough called?

Answer 18

the amplitude

Question 19

what is the distance from trough to trough or crest to crest?

Answer 19

one wavelength

Question 20

what is the number of waves to pass a point in one second called?

Answer 20

the wave frequency.

Question 21

formula for waves?

Answer 21

v=fw

Question 22

What is electromagnetic waves?

Answer 22

Electromagnetic waves are a type of energy wave that travels through space. They are created by the movement of electric charges, which produce electric and magnetic fields that move together. These waves can travel through a empty space and do not require a medium (like air or water) to move.

Question 23

What does Electromagnetic waves help in society?

Answer 23

Enable wireless communication.
Satellite communication.
High-speed data transmission.

Question 24

what is the differences between reflection and refraction?

Answer 24

Reflection: When light hits a surface and bounces back into the original medium, this is called reflection. Refraction: Refraction occurs when light passes from one medium (like air) into another medium (like water) and bends.

Question 25

What is evolution:

Answer 25

Evolution is the process by which species change over time. It explains how all living things are related through common ancestors and how they have adapted to their environments. It also accounts for the biodiversity we see today.

Question 26

Natural selection:

Answer 26

The process by which a certain species of individuals with traits better suited to their environment are more likely to survive and reproduce, passing these traits to the next generation.

Question 27

What is evolution:

Answer 27

Evolution is the process by which species change over time. It explains how all living things are related through common ancestors and how they have adapted to their environments. It also accounts for the biodiversity we see today.

Question 28

Natural selection:

Answer 28

The process by which a certain species of individuals with traits better suited to their environment are more likely to survive and reproduce, passing these traits to the next generation.

Question 29

Darwin and Wallace:

Answer 29

Darwin and Wallace helped each other, they discovered: natural selection, common descent, speciation, and adaptation

Question 30

What are the 5 tenets of natural selection and provide examples.

Answer 30

These five tenets explain how natural selection drives evolutionary change: 1. There is variation in traits.Eg: some butterflies are blue and some are orange 2.Traits are inherited.Eg: if an orange butterfly can survive better than a blue, its orange colour can be passed on to its offspring. 3.More offspring are produced than can survive (overproduction).Eg: a spider may birth a lot of little spiders but only a few of them will grow up into big spiders due to limited resources(food,) 4.Those with advantageous traits have higher survival and reproduction rates.Eg: In a sunflower field, an orange butterfly is less likely to be killed due to its orange colour blending in with its surrounding providing an advantage to hide from predators. 5.Over time, the population shows increasing adaptation to its environment.Eg: after generations, most of the butterflies are orange as this trait has helped them survive better in their environment.

Question 31

define Palaeontology and give example:

Answer 31

(fossil evidence)provides a record of the past and demonstrates how species evolved, including extinct forms that show connections between current species.Eg: fossils of dinosaurs are linked to chicken

Question 32

define Biochemical evidence and give example:

Answer 32

Biochemical evidence looks at similarities and differences in DNA, proteins, and other molecules among species. The more closely related two species are, the more similar their genetic material is, indicating a common ancestor. Eg: Humans share about 98-99% of their DNA with chimpanzees, indicating a close evolutionary relationship.

Question 33

Comparative Anatomy and give example:

Answer 33

Comparative anatomy examines similarities in the structure of different species, suggesting they evolved from a common ancestor. Homologous structures (similar structure, different function) show evolutionary connections, while analogous structures (different structure, similar function) show convergent evolution.Eg: The forelimbs of humans, whales, bats, and cats all have the same bone structure (humerus, radius, ulna, etc.)

Question 34

Comparative embryology:

Answer 34

Comparative embryology studies the development of embryos in different species. Early stages of embryonic development often show remarkable similarities, indicating that these species share a common ancestor.Eg: Human embryos, as well as those of fish, birds, and other animals, have similar stages early in development, such as the presence of gill slits and tail-like structures, even though these features may not appear in the adult form.

Question 35

Biogeography

Answer 35

Biogeography is the study of the geographical distribution of species. The way species are distributed around the world provides clues to their evolutionary history. Species that are geographically isolated tend to evolve differently, while species in similar environments can evolve similar traits due to convergent evolution.Eg: Australia is home to a unique group of marsupial mammals (like kangaroos and koalas), which evolved in isolation after the continent separated from other landmasses.

Question 36

Relative dating:

Answer 36

Relative dating is a method used by scientists to determine the age of rocks and fossils in relation to other rocks and fossils. It does not give an exact age (in years) but instead places events in sequential order.

Question 37

Law of Superposition:

Answer 37

It is a part of relative dating which states that in an undisturbed sequence of sedimentary rock layers, the oldest layers are at the bottom, and the younger layers are on top.

Question 38

Correlation:

Answer 38

similar to relative dating, but extends to the subject of matching rock layers and fossils across different geographic locations.

Question 39

Fossil formation:

Answer 39

describes the process by which an animal dies and its remains are preserved in sediments. Fossils are more likely to form in environments where rapid burial prevents decomposition and preserves the organism’s remains.

Question 40

Lamark vs Darwin:

Answer 40

Lamark: Lamarck proposed that organisms could acquire traits during their lifetime based on their needs or experiences and then pass those traits on to their offspring.Eg: As these giraffes faced competition for food, they stretched their necks to reach higher leaves in trees. Over time, the continual stretching of their necks would lead to longer necks being acquired during their lifetimes. Darwin: Darwin proposed that evolution occurs through natural selection, where individuals with advantageous traits are more likely to survive and reproduce. These beneficial traits become more common in the population over generations.Eg:Giraffes with longer necks were more likely to survive, reproduce, and pass on their genetic traits to their offspring. Over many generations, the population would evolve to have longer necks as a result of this selective pressure.

Question 41

The Geological Time Scale (GTS) and 5 major conclusions:

Answer 41

system used by geologists and paleontologists to organize Earth's history into manageable time frames. It represents the timing and relationships between events that have occurred throughout Earth's history, from its formation to the present. 5 major conclusions: 1.Life evolved from simple forms to complete forms. 2.For most of the Earth’s history, life was unicellular 3.There is more biodiversity now than in the past. 4.Life first appeared in water, then moved to land and air. 5.Humans appeared very recently in Earth’s history.

Question 42

Relate particle movement to temperature.

Answer 42

Heat energy occurs from the vibration of particles which causes a change in temperature An increase in vibration increases the temperature. A decrease in vibration decreases the temperature.

Question 43

List and describe the 3 types of energy transfer and examples:

Answer 43

Conduction: The movement of heat in solid objects-particles heat up, move more and bump into other particles. (the process of heat transfer from one object to another) Eg: When you cook an egg in a pan, the heat transfer from the hot pan to the egg to cook it. Convection: The movement of heat in fluids- hot fluids rise because they are less dense and cool fluids sink because they are more dense. (the process of hot fluid/gases going to the top and cold sink to the bottom) Eg: When you are boiling water, as the water heats up, the heated water becomes less dense so they rise to the top and the cooler and denser water sink to the bottom to be heated. Radiation: the movement of heat by waves. Eg: When you sit near a campfire, you can feel the warmth radiating from the flames, fire emits infrared radiation that travels through the air and reaches your skin, warming you.

Question 44

Distinguish between conductors and insulators and provide 2 examples of each:

Answer 44

Conductors: Substances that allow the movement of heat. E.g: copper and iron Insulators: Substances that stop the movement of heat. E.g: plastic, paper, wood

Question 45

How energy can move through a medium and why sounds cannot pass through a vacuum:

Answer 45

A source vibrates causing particles in a medium to vibrate back and forth, bumping into other particles which cause them to also vibrate. Sound waves cannot travel in a vacuum of space as there is no medium(solid, liquid, or gas) to transmit the energy to.

Question 46

Define ‘medium’

Answer 46

a medium is a substance- solid, liquid or gas

Question 47

Differences between longitudinal and transverse waves with examples:

Answer 47

Longitudinal: Particles are displaced/ move parallel to the direction that the wave travels. Eg: sound waves and earthquakes (seismic waves) Transverse: wave moves at a right angle to the way the particles are vibrating. Eg: ripples in the water and strings vibrating on a guitar.

Question 48

Outline the rise of superbugs and relate it to evolution.

Answer 48

Superbugs are bacteria that have grown resistant to several antibiotics, making them difficult to treat. The rise in superbugs could be caused by the overuse of antibiotics, incomplete course of treatment, and poor infection control practices. It is related to evolution through natural selection

Question 49

Endothermic reactions

Answer 49

Endothermic reactions absorb energy from their surroundings, typically in the form of heat which causes the energy in its surroundings to DROP.

Question 50

Exothermic reactions:

Answer 50

Exothermic reactions release energy into their surroundings, typically in the form of heat which causes the energy in its surroundings to INCREASE.

Question 51

What is rusting

Answer 51

Rusting is a chemical process that occurs when iron and its alloys (like steel) react with oxygen and moisture in the environment, leading to the formation of iron oxides, commonly known as rust.

Question 52

How do you prevent rusting reactions:

Answer 52

you can prevent rusting through alloying with non-corrosive metal.