The conservation of mass is obtained when the total mass of reactants is equal to total mass of

Chalk, limestone, marble, eggshells and seashells are made of

A. calcium hydroxide

B. calcium oxide

C. calcium carbonate

D. calcium chloride

Chemical changes are

A. reversible

B. irreversible

C. interchangeable

D. non interchangeable

If baking soda or fruit salt is mixed with vinegar, there takes place a

A. chemical reaction

B. physical reaction

C. transference

D. both a and b

Burning of fossils fuel results in the production of

A. bio gas

B. oxygen

C. carbon dioxide

D. nitrogen

At room temperature iron and sulphur

A. do no react

B. react

C. vigorously react

D. somehow react