GRADE 7 - ELEMEMENTS AND COMPOUNDS

simplified form of matter which cannot be decomposed by ordinary chemical means

• compound

• pure substance

• elements

• all of the above

simplified form of matter which cannot be decomposed by ordinary chemical means

• compound

• pure substance

• elements

• all of the above

the most abundant element in Earth’s crust and water

• oxygen

• carbon

• helium

• gas

easily shaped coz it melts when heated

• gold

• carbon

• metal

• non metals

comprises 78% of the air

• oxygen

• carbondioxide

• nitrogen

• helium

The system of chemical symbols was proposed by the great Swedish chemist________

• Jons Jacob Berzalus

• Jons Jacob Berzalius

• John Jacob Berzalius

• Jacob Benz

pure substance that can be broken down by a chemical change into simpler substance with fixed mass ratio

• element

• mixture

• pure substance

• compound

this element is a gas that is mainly used for disinfection.

• chlorine

• iodine

• sodium

• hydrogen

commonly called salt, is one of the best preservatives.

• sodium chloride

• sodium ascorbate

• nitrogen

• carbon dioxide

form of matter that cannot be separated into two different species by any physical means

• compounds

• pure substance

• elements

• all of the above