Science [1 Mark Questions]

1. The initial blue colour of copper sulphate solution is changed to light green colour of iron sulphate.
2. The initial silver colour of iron nail is changed to reddish-brown colour due to coating of copper metal on the nail.

1. Mg.
2. Cu.

High electrical conductivity.

Silver, gold and platinum are used to make jewellery b ecause all of these metals have a bright shiny surface and are resistant to corrosion.

Covalent bond.

1. Nitrogen is used by plants.
2. Carbon is used as a fuel.

X will form X 2-
Y will form Y 2+

Out of A and B, the compound whose aqueous solution cond ucts electricity will be an ionic compound.

Malleability.

Steel contains iron and carbon. This alloy of iron (steel) is hard and strong. It also rusts less readily than pure iron.

1. 1
2. 6

Hydrogen sulphide gas tarnishes silver articles.

1. Sodium oxide.
2. Magnesium oxide.

Carbonate and sulphide ores are usually converted into oxides because it is easier to obtain metals from their oxides (by reduction) than from carbonates or sulphides.

Anions.

The surface of some metals acquires a dull appearance when exposed to air b ecause of the formation of an oxide layer on the surface of the metal.

K being the lowest in the reactivity series is least reactive and is most likely to occur in a free state in nature.

Sodium > Calcium > Magnesium > Zinc > Iron > Lead > Copper

When a strip of copper metal is immersed in silver nitrate solution, the solution gradually becomes blue and a shining greyish-white deposit of silver metal is formed on copper strip.

Acidic oxides are formed when non-metals combine with oxygen.

1. Painting.
2. Applying grease or oil.
3. Galvanisation.
4. Tin and chromium plating.
5. Alloying to form stainless steel.

Aluminium.

1. Mercury.
2. Sodium.
3. Silver.
4. Mercury and Lead.

Aluminium foil.

Sulphur dioxide gas is evolved when cinnabar ore is roasted.

Carbon.

Aluminium metal does not react with water under ordinary conditions because of the presence of a thin layer of aluminium oxide on its surface.

If a strip of silver metal is kept immersed in copper sulphate solution for some time, then no reaction occurs. This shows that silver is not able to displace copper from copper sulphate solution.

Electrolytic reduction.

Ionic bond.

Stainless steel contains iron, chromium and nickel. Stainless steel does not rust at all and is strong and tough.

Aluminium oxide is electrolysed in molten state to obtain aluminium metal. Oxygen gas is evolved during the process.

Magnesium virtually has no reaction with cold water. It reacts slowly with hot water to give hydrogen gas and white magnesium hydroxide, which is only slightly soluble in water. Hydrogen gas is given out in the reaction.

Iron is extracted from haematite ore.

Low melting point.

White phosphorus.

Metals are the elements that conduct heat and electricity, and are malleable and ductile.
Example: Iron, aluminium, copper, gold and silver.

Yes.

Sulphur.

Gold and Platinum are found in nature mainly in the free state.

Iron objects are painted so that air and moisture can not come in contact with the iron objects and hence no rusting takes place.