morning work

brass is an alloy of

• A. lead and Tin

• B. iron and carbon

• C. copper and zinc

• D. magnesium and aluminium

a mixture of sodium carbonate and sodium hydrogen carbonate can be separated by fractional crystallisation because the two salts have different

• A. densities

• B. solubilitiés

• C. melting points

• D. boiling points

the atomic number of an element T is 15. which one of the following is the nature of the oxide of T

• A. acidic

• B. neutral

• C. basic

• D. atmospheric

which one of the following substances is formed when sodium is burnt in limited amount of air

• sodium oxide

• sodium peroxide

• sodium carbonate

• sodium nitrate

which one of the following allotropes of sulphur is stable above 96⁰C

• monoclinic sulphur

• rhombic sulphur

• plastice sulphur

• amorphous sulphur

theatomic number of elements W,X,Y and Z are 9,11,12 and 14 respectively. which one of the following pairs of elements can combine to form a convalent compound

• w and X

• x and y

• y and z

• z and w

in which one of the following gases will magnesium burn to form a white solid that will react with water to form ammonia

• NO2

• N2O

• NO

• N2

which one of the following properties is true about carbon and sulphur

• form covalent compounds only

• form acidic oxides only

• conduct electricity

• have allotropes

which one of the following substances can conduct electricity either in solution or molten state

• hydrogen chloride

• sugar

• ethanol

• sulphur

which one of the following metals is used in the laboratory preparation of hydrogen

• iron

• zinc

• magnesium

• potassium