SHORT ANSWER-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals

SHORT ANSWER-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals  

Q1. Why all ores are minerals but all minerals are not ores?

Ans

Ores are the minerals having high concentration of elements mostly metals. Example-Ore of Mercury, ore of Tin, ore of Zinc.

Minerals are the naturally occurring chemical substances having fixed chemical composition and crystalline structure. Example- Table salt (Sodium chloride), quartz (Silicon dioxide), limestone.

All minerals cannot be ores because they contain unwanted substances other than metals whereas all ores can be minerals as we can extract metal commercially.

Q2. Why the oxides of a high reactive metals cannot be reduced by carbon

Ans

The oxides of very reactive metals cannot be reduced with carbon. This is because these metals have more affinity (more attraction) for oxygen than carbon. so carbon is unable to remove oxygen from these metal oxides and hence cannot convert them into free metals. The highly reactive metals are extracted by the electrolytic reduction of their molten chloride.

Q3. 1.(a) Name a metal which does not stick to glass?

 (b)Name a non-metal which is good conductor of electricity?

 (c)Name the metal which is commonly used in thermit welding?

 (d)What gets deposited at the cathode, a pure or impure metal?

 (e)What is the nature of Zinc oxide?

 Ans.(i)Mercury

 (ii)Graphite

 (iii)Aluminum

(iv)A pure metal is always deposited at the cathode

(v)Zinc oxide (ZnO) is an amphoteric oxide.

Q4 .(a) What is corrosion?

(b) How is corrosion caused

 Ans. (a)The eating up of the surface of metal if kept open for a long time is called corrosion

(b)It is caused due to the eating of metals by the gasses and water vapours present in air due to the formation of certain chemical compound

Q5. State the property utilised in the following:

a. Graphite in making electrodes.

b. Electric wires are coated with polyvinyl chloride (PVC) or rubber like materials.

c. Metal alloys are used for making bells and strings of music instruments.

Ans : a. Graphite is a good conductor of electricity.

b. PVC is an insulator, protects us from electric current.

c. Alloys are stronger and more sonorous than metals and used for bells and musical instruments. They do not get rusted

Q6. Name two metals which are purified by electrolytic refining. Mention the cathode, anode and electrolyte used in the refining process. At which electrode would the pure metal be deposited?

Ans :  Cu, Zn, Al can be purified by electrolytic refining method: At cathode, pure metal is deposited. Cathode is made up of pure metal. Anode is made up of impure metal. Soluble salt of metal is used as electrolyte.

Q7. Define the terms: (a) mineral, (b) ore and (c) gangue

Ans : a. Mineral: It is a naturally occurring substance from which metal may or may not be extracted economically e.g., Mica.

b. Ores: These are naturally occurring substances from which metal can be extracted profitably e.g., Haematite.

c. Gangue: The impurities present in the ore is called gangue e.g., SiO2 .

Q8 Give one most suitable word for the following statements: a. Metal oxides which show basic as well as acidic behaviour. b. Some metals produce a sound on striking with a hard surface. c. Iodine, shining non-metal.

Ans :  a. Amploteric oxide, b. Sonorous, c. Lustrous.

Q9. Distinguish between the following: a. Electrolytic reduction and electrolytic refining. b. Mineral and ore. c. Alloys and amalgams

 Q10. Name the constituent elements of alloys: a. Brass, b. Bronze, c. Solder.

Mention one use of each alloy.

Ans

a. Brass is made up Cu and Zn. It is used for making decorative articles.

b.Bronze is made up of Cu and Sn. It is used for making statues, medals.

c. Solder it is an alloy of Pb and Sn. It is used for soldering purposes.