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1Which of the following is a product of the combustion of methane in air?

A Carbon monoxide and water B Carbon dioxide and water C Carbon and hydrogen gas D Sulphur dioxide and water

2What type of reaction occurs when an acid reacts with a metal to produce a salt and hydrogen gas?

A Synthesis B Decomposition C Single displacement D Double displacement

3Which of the following is a non‑point source of water pollution?

A Factory effluent pipe B Oil spill from a tanker C Runoff from agricultural fields D Sewage treatment plant discharge

4Deforestation contributes most directly to which environmental problem?

A Acid rain B Ozone depletion C Soil erosion D Thermal pollution

5In Mendelian genetics, what term describes the observable traits of an organism?

A Genotype B Phenotype C Allele D Gene pool

6If a pea plant is heterozygous (Tt) for tallness, what proportion of its offspring are expected to be short when self‑pollinated?

A 0% B 25% C 50% D 75%

7Which disease is caused by a virus and can be prevented by vaccination?

A Tuberculosis B Malaria C Measles D Cholera

8What is the main route of transmission for the bacterium *Mycobacterium tuberculosis*?

A Ingestion of contaminated water B Sexual contact C Airborne droplets D Vector bite

9Which phenomenon explains why a straw appears bent when placed in a glass of water?

A Diffraction B Reflection C Refraction D Interference

10The frequency of a sound wave is 500 Hz. What is its period?

A 0.002 s B 0.5 s C 2 s D 500 s