Everyday Science

A substance is a form of matter that has a uniform and definite composition. Graphite is a pure form of carbon, making it a substance. Sea water and tape water (likely meant to be tap water) are mixtures, and brass is an alloy (a mixture of metals), so they are not pure substances.

A bore is a tidal phenomenon caused when the rising tide meets the opposing flow of a river, creating a sudden and strong surge of water moving upstream. This matches option A.

Gypsum is commonly used to treat alkaline soils because it helps to displace sodium ions and improve soil structure, making the soil more suitable for cropping.

The troposphere is the lowest layer of Earth's atmosphere, containing most of the atmosphere's mass and nearly all water vapor and oxygen. It is where weather changes occur. However, it is only about 8-15 km thick, not 350 km, making option D false.

An anemometer is an instrument specifically designed to measure the velocity of wind or air flow. A speedometer measures the speed of a vehicle, an odometer measures distance traveled, and a hygrometer measures humidity.

Nuclear radiation is emitted by elements whose nuclei are unstable because unstable nuclei undergo radioactive decay to reach a more stable state, releasing radiation in the process.

Oranges are well known for being rich in vitamins, especially vitamin C, which supports immune function and skin health. They contain minimal fats and proteins, and while they have carbohydrates, vitamins are their most notable nutrient.

Galvanised iron sheets are coated with zinc to protect the iron from rusting by providing a protective layer that prevents corrosion.

Precision and accuracy are both essential in scientific work to ensure reliable and valid results. Statements B and C incorrectly suggest that one can be neglected, and D is not necessarily true as calculations may be part of planning but are not mandatory before every experiment.

Vitamin C is water-soluble and sensitive to heat, which causes it to degrade during cooking or heating processes. Vitamins B and E are also somewhat sensitive, but Vitamin C is most notably destroyed by heat. Vitamin K is fat-soluble and more stable to heat.