Materials: Metals and Non-Metals For Class 8 IMportant Question Chapter 4

Ans. (d) mercury

Ans. (c) hydrogen

Ans. (c) silver

Ans. (d) all of these

Ans. (c) both metals and non-metals

Ans. (b) metalloid

Ans. (a) ore

Ans.  (a) Sodium

Ans. (a) Aluminium

Ans. (d) zinc

Ans. (a) Sodium

Ans. (b) metalloids

Ans. (d) Calcium

Ans. (d) gold

Ans. (b) hard and solid

Ans. (d) Potassium

Ans. (d) All of these

Ans.  (c) potassium

Ans. (d) Gold

Ans. (c) Both (a) and (b)

Ans. (a) C

Ans. Magnesium burns with a white dazzling flame and a white powdery magnesium oxide is formed.

Ans. Hydrogen, oxygen, carbon, sulphur, phosphorus, etc.

Ans. Potassium and sodium

Ans. No, because copper is less reactive than zinc and will not be able to displace zinc from its salt solution.

Ans. The hydrogen gas formed on adding calcium to water sticks to the surface of calcium solid and make it float in water.

Ans. Substances having characteristic properties like malleability, ductility, sonority, conductivity, lustre, – and solidness are called metals. For example, aluminium, copper, zinc, iron, etc.

Ans. Substances which are soft and dull, i.e., non-lustrous, non-sonorous, non-ductile, non-malleable and poor conductor of heat and electricity are called non-metals. For example, oxygen, hydrogen, sulphur, etc.

Ans. Malleability is the property of metals due to which they can be beaten into thin sheets. For example, if we beat or hammer any metal like aluminium, zinc, iron, copper, etc., it become longer and larger but does not break. Thin sheets can be obtained by this process.

Ans. Aluminium is a metal and hence possesses malleability property. It can be beaten into thin sheets and can be folded into any shape. It is cheaper than other malleable metals and does not react with food items. That is why it is used as wrapping materials for food items.

Ans.

• Metals are malleable and give thin sheets after hammering whereas non-metals are brittle and give no sheets.
• Metals are ductile and can be drawn into wires whereas non-metals are non-ductile and can’t be drawn into wires.
• Metals are sonorous and used in ringing bells whereas non-metals are non-sonorous and cannot be used in ringing bells.
• Metals are good conductors of heat and electricity while non-metals are poor conductors.

Ans. Non-metals react with oxygen to form acidic oxides. But most of the non-metals reacts with oxygen on ignition.The equations follow as:

Ans. Metals react with acids to form respective salts along with evolution of hydrogen gas that burns with a pop sound. The equation are as follows:  

There are some metals like copper, silver, gold and platinum that do not liberate hydrogen with acids. Generally, non-metals do not react with acids.

Ans.

Ans.

(i) Reaction with oxygen: Non-metals react with oxygen to form acidic oxides. But most of them do this on ignition. For example,

(ii)They form negative ions and are good oxidising agents.
(iii) Reaction with water: Non-metals do not react with water.
(iv) Reaction with acids and bases: Generally, non-metals do not react with acids and bases. How – ever, sometimes some complex reactions take place between non-metals and bases.