Class 10 Chemistry Chapter 3 - Metals and Non Metals Most Important Questions

 Class 10 - Metals and Non metals

Most important questions:- 

Q 1 .Write the 5 properties of metals with examples.

Answer :- 

• Metals are lustrous. 

E.g - Silver

• Metals are Good Conductor of heat .

E.g - Silver and copper.

• Metals are Ductile .

E.g - Gold 

• Metals are malleable.

E.g - Gold and Silver 

• Metals are Hard .

E.g - chromium 

Q2 . Which of the Following non metal is Lustrous :- 

a) Carbon 

b) Iodine 

c) Chlorine

d) Graphite

Answer - b) Iodine

Q3. Which metal remains in liquid form at room temperature ? 

Answer - Mercury

Q4. Which Non metal is best conductor of electricity? 

Answer - Graphite 

Q5 .Which Non metal is best conductor of heat ? 

Answer - Diamond 

Q6. Generally, when metals are treated with mineral acids, hydrogen gas is liberated, but when metals (except Mn and Mg) are treated with HNO3, hydrogen is not liberated. Why?

Answer:

Most metals do not react with HNO3 because nitric acid is a potent oxidising agent. Hence, when metals (except Mn and Mg) are treated with nitric acid, hydrogen gas is not liberated. Only magnesium and manganese can produce hydrogen gas with very dilute nitric acid.

Q7. When a metal X is treated with cold water, it gives a basic salt Y with the molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Answer:

X is Na because the molecular mass of NaOH is 40.

Na (23) + O (16) → NaOH (40)

Hence,

X is Sodium.

Y is Sodium hydroxide.

Z is hydrogen, which catches fire when it reacts with water.

2 Na + 2 H2O → 2 NaOH + H2.

Here oxygen is losing hydrogens, so it is oxidised. The Na has gained oxygen, so it is reduced. Therefore, it is a redox reaction and an H2 displacement reaction. Redox reactions are reactions in which one species is reduced and another is oxidised. Consequently, the oxidation state of the species involved must change.

Q8. An element A reacts with water to form a compound B used in whitewashing. The compound B on heating forms an oxide C which gives back B on treatment with water. Identify A, B and C and give the reactions involved.

Answer:

A is calcium. It reacts with water to give calcium hydroxide.

B is calcium hydroxide. It is used for whitewashing.

C is calcium oxide.

The reactions are as follows:

Ca + 2 H2O → Ca(OH)2 + H2

Ca(OH)2 → CaO + H2O

CaO + H2O → Ca(OH)2

Q9. What is Ionic Bond ? 

Answer - 

When metals and non metals react with each other by losing or gaining electron is called ionic bond .

Q10. Two ores A and B were taken. On heating, ore A gives CO, whereas ore B gives SO2. What steps will you take to convert them into metals?

Answer:

A carbonate ore is calcinated to obtain the oxide of the metal. When a carbonate ore is heated, we get carbon dioxide. The following equation shows the calcination of zinc carbonate.

ZnCO3 → ZnO + CO2

When a sulphide ore is roasted, we get Sulphur dioxide. Zinc sulphide is roasted to obtain zinc oxide.

2 ZnS + 3 O2 → 2 ZnO + 2 SO2.

After any of the above steps, zinc oxide is reduced to obtain pure zinc.

ZnO + C → Zn + CO