Grade 8 Science: 10 Free Practice Questions

Answer: Boundary X
At X the plates move in opposite directions along the boundary, one toward the bottom and one toward the top of the map. They slide past each other, which is a transform boundary. Crust is neither made nor destroyed there, but earthquakes are common. At Y plate 3 moves toward plate 2, so crust is pushed together and eventually destroyed. Check whether the arrows approach, separate or run alongside.

Answer: 5 chains
Follow the arrows from Plankton to Shark and list each complete path. Plankton, Small fish, Shark is one. Plankton, Small fish, Tuna, Shark is a second. Through Shrimp there are three more: Shrimp to Small fish to Shark, Shrimp to Small fish to Tuna to Shark, and Shrimp to Crab to Tuna to Shark. That makes five.

Answer: The pitch gets higher and the wavelength gets shorter
The pitch gets higher and the wavelength gets shorter. Pitch follows frequency. With the speed fixed, speed equals frequency times wavelength, so when frequency rises the wavelength must shrink. Loudness depends on amplitude, which did not change. If you chose a longer wavelength, you treated frequency and wavelength as rising together. At constant speed, they move in opposite directions.

Answer: Town R
Town R is in a cell with the lightest shading, which the key labels Low. Town P and town T are in Moderate cells, and town Q is on the fault in a High cell. Hazard is highest close to the fault and falls with distance. The deciding step is matching each town's shading to the key, not only judging how near it looks to the fault line.

Answer: Letter B
Photosynthesis happens in chloroplasts, the green organelles that contain chlorophyll and capture light energy. In the diagram, the leader line from this letter ends on a small grey circle of the chloroplast type. The nucleus, cell wall and large vacuole have other jobs: storing DNA, giving support and storing water. Always follow each line to the exact structure it touches.

Answer: Wind
Wind is renewable because the Sun keeps heating Earth unevenly, and that keeps air moving. The supply is replaced continually, at least as fast as people use it. Coal, petroleum and natural gas are fossil fuels that formed from ancient organisms over millions of years, so they are replaced far more slowly than they are used. Renewable describes how fast a resource is replaced, not whether it is clean.

Answer: The second: the mass leaves as gases and is conserved.
Nothing is destroyed. The wax combines with oxygen and leaves as carbon dioxide and water vapour, which drift away invisibly, so the candle shrinks while the total mass is unchanged. Collect and weigh those gases and the books balance. This is the clearest everyday case where conservation of mass looks false and is not, because the products are invisible.

Answer: An atom
An atom is the smallest particle of an element that still behaves like that element. A grain of powder looks small but contains billions of atoms. A water molecule is the smallest particle of a compound, not of an element, and a mixture is not a single particle at all. Atom for an element, molecule for most compounds.

Answer: A book sitting on a high shelf
Gravitational potential energy depends on height above the ground, so the book on the shelf has it. The sliding book is moving along the floor, which gives it kinetic energy instead, and the book on the ground has no height to fall through. The rubber band stores elastic potential energy, a different store altogether.

Answer: Hydropower
First keep only the sources marked Yes for working at night: coal, natural gas and hydropower. Of these, hydropower releases 24 g of CO2 per kWh, far below natural gas at 500 g and coal at 1000 g. Wind has the lowest CO2 overall, but it is marked Sometimes, so it fails the night requirement. Apply the filter first and then compare.