Which one of the following substances is not a mixture?
- (a)Tin
- (b)Sea water
- (c)Soil
- (d)Air
Correct - A, Tin. Tin is a chemical ELEMENT (symbol Sn) - a pure substance made of only one kind of atom - so it is not a mixture. Sea water (water with dissolved salts), soil (minerals, organic matter, air and water) and air (nitrogen, oxygen, argon, carbon dioxide and more) are each mixtures of two or more substances. Therefore tin is the odd one out.
- (b)Sea water — Sea water is a mixture - mainly water with dissolved sodium chloride and other salts - so it is not the answer.
- (c)Soil — Soil is a heterogeneous mixture of mineral particles, humus, water, air and living matter.
- (d)Air — Air is a homogeneous mixture of gases, about 78% nitrogen and 21% oxygen with argon and carbon dioxide.
Matter is classified as pure substances (elements and compounds) or mixtures. An element such as tin is a pure substance of a single kind of atom and cannot be separated into simpler substances by physical means. Mixtures - sea water, soil and air - contain two or more substances that are not chemically combined and can be separated by physical methods.
Find the pure substance among everyday mixtures. Sea water, soil and air are classic examples of mixtures, whereas tin, a metallic element, is a single pure substance.
- Tin (symbol Sn) is a metallic element - a pure substance, not a mixture.
- Air is a homogeneous mixture of gases, roughly 78% nitrogen and 21% oxygen plus argon and carbon dioxide.
- Sea water is water with dissolved salts, chiefly sodium chloride.
- Soil is a heterogeneous mixture of minerals, organic matter, water and air.
- Assuming a metal must be an alloy (a mixture) - pure tin is an element, while brass and bronze are alloys.
- Treating air or sea water as pure substances rather than mixtures.
Asked by picking the pure substance (element or compound) among a list of mixtures, or vice versa.
No directly related past PYQ was found.
- practice — not a real PYQ
Which one of the following is a pure substance and not a mixture?
- (a)Brass
- (b)Bronze
- (c)Copper
- (d)Air
Answer(c) Copper - a chemical element; brass and bronze are alloys and air is a mixture.
- practice — not a real PYQ
Air is best classified as
- (a)a compound
- (b)an element
- (c)a homogeneous mixture
- (d)a heterogeneous mixture
Answer(c) a homogeneous mixture of gases.