Periodic Table, Materials & Earth Science

Which of these best describes an exothermic reaction?

• AA reaction that needs a catalyst present in order to happen
• BA reaction that transfers energy to the surroundings, so the surroundings warm up✓
• CA reaction that takes in energy from the surroundings, so the surroundings cool down
• DA reaction that produces a brand new element from the reactants

Answer: Exothermic reactions transfer energy to the surroundings, so the surroundings get warmer. Endothermic reactions do the opposite, taking energy in and cooling the surroundings. A catalyst can speed up a reaction but is not what makes it exothermic, and reactions rearrange existing atoms rather than creating new elements.

In an endothermic reaction, what happens to the temperature of the surroundings?

• AIt increases, because the reaction releases energy into the surroundings
• BIt decreases, because the reaction absorbs energy from the surroundings✓
• CIt stays exactly the same throughout the whole reaction
• DIt only changes if the reaction happens to produce a gas

Answer: An endothermic reaction takes in energy from its surroundings, so the surroundings become cooler as the reaction proceeds. A rise in surrounding temperature is the sign of an exothermic reaction instead. The temperature change happens because of the energy transfer itself, not because of any gas produced.

When ice melts into water, what happens to the energy of the ice?

• AThe ice's energy stays fixed because melting is a physical change
• BThe ice loses mass, which lowers its total stored energy
• CThe ice absorbs energy from its surroundings as it changes state✓
• DThe ice releases energy into its surroundings as it changes state

Answer: Melting is a change of state that requires energy to be absorbed from the surroundings, which is why melting ice cools a drink. Freezing is the reverse process and releases energy instead. Being a physical rather than a chemical change does not stop energy being transferred during the change of state.

Burning natural gas in a boiler is an example of which type of energy change?

• AA reaction with no overall change in energy at any point in the process
• BA change of state occurring rather than a true chemical reaction
• CAn exothermic reaction, since it releases energy as heat✓
• DAn endothermic reaction, since it absorbs energy from the surroundings as heat

Answer: Burning, or combustion, is a chemical reaction that transfers energy to the surroundings as heat, making it exothermic. An endothermic change would absorb energy and cool its surroundings instead. Combustion is a chemical reaction, not simply a change of state such as melting or boiling.

What was significant about Mendeleev's early Periodic Table?

• AHe arranged the elements in alphabetical order of their names
• BHe grouped elements by their colour and smell
• CHe placed the metals below the non-metals in one long column
• DHe left gaps for elements that had not yet been discovered✓

Answer: Mendeleev arranged elements by their properties and left gaps in his table, correctly predicting that undiscovered elements would later be found to fill them. He did not use alphabetical order, which would break up elements with similar properties. Colour and smell alone were not the basis of his arrangement.

In the Periodic Table, what is a vertical column of elements called?

• AA group✓
• BA period
• CA series
• DA block

Answer: A vertical column of elements in the Periodic Table is called a group, and elements in the same group tend to share chemical properties. A horizontal row is called a period instead. Series and block are not the standard terms used for a column.

Why do elements in the same group of the Periodic Table often react in similar ways?

• AThey have identical melting points and boiling points
• BThey were discovered in the same country during the same century
• CThey have similar chemical properties because of their position in the table✓
• DThey are radioactive and unstable at room temperature

Answer: Elements in the same group share similar chemical properties, which is exactly why the Periodic Table is arranged that way. Where or when an element was discovered has no bearing on how it reacts. Elements in a group can have very different melting points, and most are not radioactive at all.

Which set of properties best describes most metals?

• ADull and brittle, and generally poor conductors of both heat and electricity
• BSoft and colourless, and usually found as gases at room temperature
• CTransparent and flexible, and unable to conduct electricity
• DShiny, malleable, and good conductors of heat and electricity✓

Answer: Most metals are shiny, can be hammered into shape without shattering, and conduct heat and electricity well. Dull, brittle materials that conduct poorly are typical of non-metals instead. Metals are not usually transparent, and almost all are solids at room temperature rather than gases.

Which of these is a typical property of non-metals?

• AThey can be hammered into thin sheets without breaking
• BThey are often shiny in appearance and are excellent conductors of electricity
• CThey are often dull in appearance and are poor conductors of electricity✓
• DThey have unusually high melting points compared with metals

Answer: Non-metals are typically dull rather than shiny and conduct electricity poorly, unlike most metals. Being shiny and a good conductor is a metallic property, not a non-metallic one. Non-metals are usually brittle rather than able to be hammered into sheets, and their melting points vary widely.

Why is the Periodic Table useful for predicting how an element will react?

• AElements in the same group tend to show similar reaction patterns✓
• BThe table lists the exact temperature each element will melt at
• CElements react according to when they were first discovered
• DElements react in exactly the same way as each other, regardless of position

Answer: Because elements in the same group behave in similar ways, knowing how one element reacts helps predict how others in that group will react. Reaction behaviour clearly differs between elements, so it cannot be the same for all of them. Melting points are not listed on a standard Periodic Table.

What is generally true about the oxides formed by metals and by non-metals?

• AMetal oxides tend to be acidic, while non-metal oxides tend to be basic
• BBoth metal and non-metal oxides are always completely neutral
• CMetal oxides tend to be basic, while non-metal oxides tend to be acidic✓
• DNeither metal nor non-metal oxides can react with acids or alkalis

Answer: Metal oxides are generally basic and can react with acids, while non-metal oxides are generally acidic. Swapping this round, so that metal oxides are acidic, is a common mix-up but is the wrong way around. Many oxides are far from neutral and do react with acids or alkalis.

What does the reactivity series show?

• AThe order of how reactive different metals, and carbon, are✓
• BThe order of how heavy different metals are, from lightest to heaviest
• CThe order of how expensive different metals are to buy
• DThe order in which elements were first discovered by scientists

Answer: The reactivity series ranks metals, and carbon, from most reactive to least reactive, which helps predict how they behave in reactions. It is not based on the date of discovery, the mass of the metal, or its price. Reactivity depends on how readily an element reacts, not on these other factors.

How can carbon be used to obtain some metals from their metal oxides?

• ACarbon is less reactive than the metal, so it displaces the metal from its oxide
• BCarbon dissolves the metal oxide completely, leaving no metal behind
• CCarbon melts the metal oxide so that the pure metal simply drips out
• DCarbon is more reactive than the metal, so it displaces the metal from its oxide✓

Answer: If carbon is more reactive than a metal, it can take the place of that metal in its oxide, releasing the pure metal in a displacement reaction. A less reactive substance cannot displace a more reactive one, so the reverse statement is wrong. This process works through a chemical reaction, not simple melting or dissolving.

Why can carbon not be used to extract a metal that is more reactive than carbon itself?

• AA more reactive element cannot displace a less reactive metal from its oxide
• BCarbon reacts with water long before it can reach the metal oxide
• CThe metal oxide would first need to be cooled to below freezing
• DA less reactive element cannot displace a more reactive metal from its oxide✓

Answer: In the reactivity series, a less reactive element cannot push a more reactive metal out of its oxide, so carbon fails to extract metals above it. The statement with more and less reactive swapped round describes the opposite, working case instead. Water and freezing temperatures are not the reason this extraction fails.

Which properties are typical of ceramics such as pottery or brick?

• AHard, brittle, and able to withstand high temperatures✓
• BFlexible, transparent, and excellent conductors of electricity
• CLightweight, magnetic, and highly reactive with water
• DSoft, stretchy, and easily melted at low temperatures

Answer: Ceramics such as pottery and brick are hard and brittle materials that can withstand high temperatures without melting. This is the opposite of being soft and easily melted at low temperature. Ceramics are not usually flexible, magnetic, or reactive with water, and they are poor conductors of electricity.

Which properties are typical of polymers such as polythene?

• AThey can often be moulded into shapes and are generally flexible✓
• BThey only ever occur naturally in the environment and cannot be manufactured
• CThey shatter very easily and can never be reshaped again once they have set
• DThey conduct electricity extremely well once they have been fully melted down

Answer: Polymers such as polythene are generally flexible and can be moulded into useful shapes, unlike brittle materials that shatter. Polymers are poor electrical conductors, even when molten. Many everyday polymers, including polythene, are manufactured rather than occurring naturally.

What is a composite material such as fibreglass or concrete?

• AA material made from a single pure element with no other substances
• BA material that can only ever form naturally through the rock cycle
• CA material that always conducts electricity better than pure metals
• DA material made by combining two or more materials to get better properties✓

Answer: A composite is made by combining two or more different materials so that the result has more useful properties than either material alone, as in fibreglass or concrete. It is not a single pure element. Composites such as concrete are manufactured, and they do not conduct electricity better than metals.

Which layers make up the structure of the Earth, moving from the outside in?

• AMantle, crust, and ocean
• BCrust, core, and mantle
• CCrust, mantle, and core✓
• DAtmosphere, crust, and mantle

Answer: The Earth is structured as a thin outer crust, a thick mantle beneath it, and a core at the centre. Placing the core before the mantle gets the order the wrong way round. The atmosphere and oceans sit above the crust rather than being layers of the Earth's solid structure itself.

How are igneous rocks formed?

• ABy the slow compacting and cementing together of layers of loose sediment
• BBy the very slow evaporation of seawater that takes place over millions of years
• CBy the cooling and solidifying of molten rock such as magma or lava✓
• DBy existing rock being gradually changed by intense heat and high pressure

Answer: Igneous rocks form when molten rock, whether magma underground or lava at the surface, cools and solidifies. Compacted, cemented sediment describes sedimentary rock instead, and rock altered by heat and pressure describes metamorphic rock. Evaporating seawater is not how any rock type in the rock cycle forms.

Which feature is most typical of sedimentary rocks?

• AThey often form in layers and can contain fossils✓
• BThey cannot be broken down or weathered over time
• CThey are always harder than igneous or metamorphic rocks
• DThey form only from magma cooling deep underground

Answer: Sedimentary rocks build up in layers from compacted and cemented sediment, and fossils are often preserved within those layers. Forming from cooling magma describes igneous rock, not sedimentary rock. Sedimentary rocks are typically softer than igneous or metamorphic rocks and can still be weathered over time.

What causes metamorphic rocks such as marble to form?

• AExisting rock is changed by intense heat and pressure over time✓
• BMolten rock cools and solidifies quickly at the Earth's surface
• CExisting rock is fully dissolved in seawater over millions of years
• DLoose sediment is simply compacted without any heating at all

Answer: Metamorphic rock forms when existing rock is transformed by intense heat and pressure, without fully melting. Dissolving in seawater is not part of the rock cycle. Molten rock cooling describes igneous rock, and sediment compacted without heat describes sedimentary rock, not metamorphic rock.

Why is recycling metals and other Earth resources important?

• ABecause Earth's resources such as metal ores are limited✓
• BBecause recycled metals, once melted down, become more reactive
• CBecause Earth's resources are unlimited and can never run out
• DBecause recycling changes the chemical formula of the metal

Answer: The Earth has a limited supply of resources such as metal ores, so recycling helps make them last longer. Saying resources are unlimited is the opposite of why recycling matters. Recycling does not make a metal more reactive, and melting a metal down does not change its chemical formula.

Which processes move carbon between the atmosphere, living things and the oceans in the carbon cycle?

• AMelting, freezing, boiling, and condensing
• BEvaporation, condensation, precipitation, and collection
• CPhotosynthesis, respiration, combustion, and decay✓
• DErosion, transport, deposition, and compaction

Answer: Carbon moves through the carbon cycle via processes such as photosynthesis, respiration, combustion and decay, which take carbon into and out of living things and the atmosphere. Evaporation, condensation, precipitation and collection instead describe the water cycle. The other lists describe changes of state or the formation of sedimentary rock, not the carbon cycle.

What are the two main gases that make up the Earth's atmosphere?

• ANitrogen and oxygen✓
• BOxygen and hydrogen
• COxygen and CO2
• DNitrogen and CO2

Answer: The Earth's atmosphere is mostly nitrogen, with oxygen making up most of the rest, and only small amounts of other gases such as carbon dioxide and argon. Carbon dioxide is present but only in a very small proportion, not as one of the two main gases. Hydrogen is not a major part of the atmosphere either.

How does burning fossil fuels affect the Earth's atmosphere?

• AIt has no measurable effect whatsoever on the overall composition of the atmosphere
• BIt permanently removes nitrogen gas from the Earth's atmosphere altogether
• CIt decreases the amount of carbon dioxide, which actually cools the climate down
• DIt increases the amount of carbon dioxide, which affects the climate✓

Answer: Burning fossil fuels releases carbon dioxide into the atmosphere, and this build-up is linked to changes in the climate. This is the opposite of decreasing carbon dioxide, which would not happen from burning fuels. Burning fossil fuels does not remove nitrogen, and it clearly does change the atmosphere's composition.

What does the rock cycle describe?

• AThe continuous transformation of rocks between igneous, sedimentary and metamorphic types✓
• BThe one-way transformation of igneous rock directly into ordinary garden soil
• CThe continuous, large-scale transformation of ordinary rocks into pure metals
• DThe daily cycle of rocks heating up in the sun and cooling down again at night

Answer: The rock cycle describes how rocks are continually transformed between igneous, sedimentary and metamorphic types over long periods of time through processes such as heating, cooling, weathering and compaction. Turning into pure metal is not part of this cycle. The rock cycle is not one-way, and it works over very long timescales rather than a single day.