NIOS Class 10 Science & Tech — Flashcards for Quick Revision

A: Measurement is a kind of counting. It means counting how many times a chosen standard scale is used to measure a physical quantity.

A: Measurement is necessary for accurate buying and selling, cooking, stitching, sports, travelling, and scientific calculations. It helps avoid confusion and conflict.

A: A unit is a measure, device, or scale in terms of which a physical quantity is measured.

A: Matter is anything that has mass and occupies space. A book, water, air, and a stone are all matter.

A: Air has mass and it occupies space inside the bag. Since both conditions are true, air is matter.

A: A substance is a pure kind of matter having only one kind of constituent particle, such as an atom or molecule.

A: In every chemical reaction, the total mass of reactants is equal to the total mass of products. Lavoisier established this by heating mercury in a sealed flask and comparing the masses before and afte

A: A pure compound always contains the same elements combined in the same fixed proportion by mass, no matter where it comes from or how it is prepared. For example, pure water always has hydrogen and ox

A: Because water is a pure compound with a fixed composition. Its mass composition is always 11.11% hydrogen and 88.89% oxygen, so the mass ratio of hydrogen to oxygen remains 1:8.