Chapter-4 Metals and non Metals

1. Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen

Explanation:

 a) Zinc

In this case, the nonmetals phosphorus, sulphur, and oxygen are nonmetals without malleability and ductility, but zinc is a metal having both.


2. Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.

Explanation :

 (c) Generally, metals are ductile.

When a substance has ductility, it can be pulled into fine wires. Mercury is the exception to the rule that metals are ductile.


3. Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene

Explanation:

a) Because aluminium is flexible and can be drawn into thin sheets, food items are often wrapped in aluminium foil.

b) Metals are used in the construction of immersion rods for heating liquids because they are efficient heat- and electricity-conductors.

c) Since zinc is more reactive than copper, it cannot be removed from its salt solution by copper.

d) Because salt and potassium are very reactive metals that easily ignite when exposed to oxygen in the air, they are stored in kerosene.


4. What happens when

(a) Dilute sulphuric acid is poured on a copper plate?

(b) Iron nails are placed in a copper sulphate solution?

(c) Write word equations of the reactions involved

Explanation:

I Pouring diluted sulfuric acid onto a copper plate results in no reaction. Yet, when concentrated sulfuric acid is applied to a copper surface, hydrogen gas is produced along with the growth of crystals of copper sulphate that are blue in colour. 

Cu + H2SO4 (conc.) -> CuSO4 + H2 

is the chemical formula for the reaction between concentrated sulfuric acid and copper.

ii) Copper is displaced from copper sulphate by iron, which is more reactive. In this reaction, copper deposits on the iron nail and the blue hue of copper sulphate fades.

Fe + CuSO4 = Cu+ FeSO4


5.One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Explanation:

The gold jewellery must be dipped into aqua regia in order to be polished (a mixture of hydrochloric acid and nitric acid). The outer layer of gold melts when submerged in aqua regia, revealing an interior layer that is lustrous. The layer's dissolution results in a decrease in the jewelry's weight.


6.Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down the word equations of all the reactions taking place in this process.

Explanation:

Using wet litmus paper, she can determine the type of gas present. If the gas causes the blue litmus paper to turn red after coming into touch with it, it is acidic. According to this, it is fundamental if it turns the red litmus into blue.

(b) I Carbon + Oxygen = CO2 (ii) CO2 + Lime water = MILKY


7. What are the differences between metals and non-metals? Explain on the basis of their physical properties.

Explanation:

While non-metals are brittle and produce no sheets after being hammered, metals are pliable and produce thin sheets.

Non-metals lack ductility and cannot be pulled into wires, whereas metals are ductile and can be.

Non-metals are not sonorous and cannot be used to ring bells, but metals are sonorous and can.

Non-metals are weak conductors of electricity and heat compared to metals.


8. How do metals and non-metals react with water?

Explanation:

When metals interact with water, they form their hydroxides, oxides, and hydrogen. Cold water and sodium and potassium react, creating a lot of heat in the process. Iron and boiling water cause a reaction with magnesium. Silver, platinum, and gold do not react with water. Water and non-metals do not interact.

9. How do metals and non-metals react with bases?

Explanation:

A large majority of metals don't react with bas

es. However, some metals, such as sodium hydroxide (NaOH), lead, and zinc, react with strong bases to produce complex salts and hydrogen.

In general, non-metals and bases do not interact. With non-metals and bases, complicated reactions can occasionally occur.

Question 10:

10. What are main uses of metals?
or
How are metals useful to us?

Explanation:

We may use metals in a variety of ways. For instance,


Metals are used to produce wires, appliances, cooking utensils, and cooking pots due to their thermal and electrical conductivity. Aluminum and copper, for instance, are frequently utilised for these things.

Aluminum is used as packaging and wrapping material. Metals like iron and steel are used in a variety of tools, machinery, pipes, rods, sheets, doors, windows, and construction projects like bridges, roads, and buildings. Automobiles, aeroplanes, and other vehicles all use it.

Jewelry and other decorative goods are made of metals like gold, silver, and platinum.

Galvanization and dry cell processes employ zinc, and electroplating uses chromium.

Batteries and electrodes are both made of lead.


11. What are the main uses of non-metals?
or
How are non-metals useful to us?

Explanation:

Non-metals are equally as crucial to our existence as metals are. They assist us in numerous ways. For instance,

We breathe oxygen, which is essential for our life and the lives of all other living things. No living thing can exist on this planet without it.Plants must have CO2, a non-metal oxide, in order to perform photosynthesis.

In fertilisers, non-metals like nitrogen and phosphorus are utilised to increase plant output. Both fireworks and matchsticks are made with phosphorus.

The purple-colored solution used to treat wounds contains a non-metal, such as iodine. Because of its fungicidal qualities, sulphur is often utilised to make ointments and skin medications.

Chlorine is a non-metal that is used in the treatment of water. because it has bleached

With powder.


12. Why does calcium float in water?

Explanation:

Calcium solid floats in water because of the adhesion of the hydrogen gas produced when calcium is added to water.

13. Zinc sulphate forms a colourless solution in water. Will you observe any colour on adding copper turn-ing in it?

Explanation:

No, copper won't be able to remove zinc from its salt solution since it is less reactive than zinc.