science - term 4 exam

Which gas must be present for a substance to burn?

Oxygen

What is a photovoltaic cell?

An electronic device that converts sunlight directly into electrical energy.

What’s an ammeter?

A instrument used to measure electric current

What’s a series curcuit?

an electrical pathway where all components are connected end-to-end in a single loop

What is an endothermic reaction?

A chemical reaction that absorbs heat from its surroundings.

What is atomic mass?

The mass of an atom measured in atomic mass units ($\text{amu}$), approximately equal to the total number of protons plus neutrons in an individual atom.

What is a synthesis reaction?

A chemical reaction where simpler substances join together to form a more complex substance.

What is a decomposition reaction?

A chemical reaction where a complex substance breaks down into simpler substances.

What is a displacement reaction?

A chemical reaction where a more reactive element replaces another element in a compound.

What happens when an acid reacts with a base?

A neutralisation reaction occurs, producing a salt and water.

What are reactants in a chemical reaction?

The starting substances present at the beginning of a chemical reaction.

What are products in a chemical reaction?

The new substances formed as a result of a chemical reaction.

What are consumers?

Organisms that obtain energy and nutrients by feeding on other organisms.

What are producers?

Organisms (such as plants) that make their own food, typically through photosynthesis.

What are predators?

Animals that hunt, kill, and eat other animals for food.

What are decomposers?

Organisms that break down dead plant and animal matter as well as waste, recycling nutrients back into the environment.

What is a mutualistic relationship?

A symbiotic relationship between two different organisms where both species benefit.

What is a commensalism relationship?

One organism benefits and the other is unaffected

What is a parasitism relationship?

One organism is benefited and the other is harmed

What are some human impacts on the environment?

Global warming/climate change - Burning fossil fuels release large amounts of carbon dioxide and greenhouse gases

Deforestation/habitat loss - cutting down forests for mining, agriculture and urban expansion destroys wildlife habitats and reduces oxygen production

Pollution - Industrial waste, agricultural run off and vechile emissions contaminate the air, soil, and ecosystems.

What’s ohms law?

Voltage = current times resistance

V=I*R

What is nuclear fusion?

A nuclear reaction where two small atomic nuclei combine to form a larger nucleus, releasing a large amount of energy.

What is nuclear fission?

A nuclear reaction where a large, unstable atomic nucleus splits into smaller nuclei, releasing energy.

What is combustion?

A chemical reaction where a fuel reacts rapidly with oxygen, releasing energy in the form of heat and light.

What is the difference between independent and dependent variables?

• Independent variable: The variable that is deliberately changed or manipulated in an experiment.
• Dependent variable: The variable that is measured or observed to see the effect of the change.

Which natural indicator can be prepared using red cabbage?

A natural pH indicator.

What colour does phenolphthalein turn in an alkaline solution?

Pink.

What is a voltmeter?

An instrument used to measure the voltage (potential difference) across a component in an electric circuit.

What is the difference between AC and DC current?

• AC (Alternating Current): Electric current that repeatedly reverses its direction.
• DC (Direct Current): Electric current that flows in one constant direction only.

What is a food chain?

A diagram that shows the feeding relationships and the flow of energy from one organism to another in an ecosystem.

What products are formed when an acid reacts with a metal carbonate?

A salt, water, and carbon dioxide gas.

Is iron more reactive or gold?

Iron.

What is an acidic solution?

A solution that has a pH value below $7$.

What is an alkaline solution?

A solution that has a pH value above $7$.

What is a neutral solution?

A solution that has a pH value equal to exactly $7$.

What is an indicator?

A substance that changes colour depending on whether it is placed in an acidic or alkaline environment.

What is the atomic number?

The number of protons found in the nucleus of an atom.

What are electromagnetic waves?

Transverse waves that transfer energy through space and do not require a material medium to propagate.

What is the speed of electromagnetic waves in a vacuum?

$$3 \times 10^8\,\text{m/s}$$

What are the key properties of electromagnetic waves?

• They are transverse waves.
• They do not require a medium to travel (can travel through a vacuum).
• Their electric and magnetic fields oscillate perpendicular to each other.

What are the characteristics of alpha ($\alpha$) particles?

• Composed of $2$ protons and $2$ neutrons (a helium nucleus).
• Have a charge of $+2$.
• Relatively heavy and slow-moving.
• Low penetrating power (stopped by a sheet of paper).
• Strongly ionising.
• Most hazardous if ingested or inhaled.

What are the characteristics of beta ($\beta$) particles?

• Fast-moving electrons.
• Have a charge of $-1$.
• Small mass.
• Moderate penetrating power (stopped by a few millimetres of aluminium).
• Moderately ionising.

What are the characteristics of gamma ($\gamma$) rays?

• High-energy electromagnetic radiation with $0$ charge and no mass.
• Weakly ionising.
• Very high penetrating power (only absorbed by thick lead or concrete).

What is ionisation?

The process by which an atom or molecule gains or loses electrons to form an ion.

What are isotopes?

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers (different number of neutrons).

What are radioisotopes?

Unstable isotopes that decay spontaneously by emitting nuclear radiation.

What’s a precipitation reaction?

A chemical reaction in an aqueous solution where two clear, dissolved salt solutions are mixed together to form an insoluble solid called a precipitate

What’s a displacement reaction?

A chemical reaction in which a more reactive element pushes a less reactive element out of its compound. The element that is displaced becomes a solid element

What is the main observable sign that a displacement reaction has taken place?

A metal precipitate form or a colour change occurs

What is the reactivity series?

Potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, led, hydrogen, copper, silver, gold

Please stop calling me a careless zebra instead try learning how copper saves gold