NCERT Class X Science Class: Chapter –3. Metals and Nonmetals– Part-9

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Question 50:

A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming

  1. Identify A, B and C

  2. To which Group of Periodic table does A belong?

Answer:

  1. A is carbon, B is carbon monoxide and C is carbon dioxide

  2. A belongs to Group – 14 of the Periodic table

Question 51:

Give two examples each of the metals that are good conductors and poor conductors of heat respectively.

Answer:

  1. Good conductor: Silver (Ag) and Copper (Cu).

    Image the good conductors

    Image the Good Conductors

    Image the good conductors

  2. Poor conductor: Mercury (Hg) and Lead (Pb):

    Images show in Poor conductor

    Images Show in Poor Conductor

    Images show in Poor conductor

Question 52:

Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than

Answer:

Following are the metals and non-metals, which exist in liquid state at room temperature.

Metal – Mercury (Hg)

Non-metal – Bromine (Br)

Images show in metal and Non-metal

Images Show in Metal and Non-Metal

Images show in metal and Non-metal

Two metals with melting points less than are Cesium and Gallium

Images show in Two metals with melting points

Images Show in Two Metals with Melting Points

Images show in Two metals with melting points

Question 53:

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

Answer:

Element A is calcium (Ca). When it reacts with water, it forms calcium hydroxide. Thus, compound B is calcium hydroxide , which is used in white washing.

Therefore,

Compound B on heating gives

Thus, C is calcium oxide

on treatment with water gives back .

Question 54:

An alkali metal A gives a compound B on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.

Answer:

For A:

Alkali metals are sodium, potassium, lithium etc.

On reacting with water, they give metal hydroxide.

Hydroxide molecular mass

As molecular mass of the metal hydroxide is 40, n = 1 or 2, and correspondingly the molecular mass of metal is 23 or 6.

That is metal A is either sodium or lithium

For B:

Sodium hydroxide or lithium hydroxide. Lithium hydroxide - molecular mass is not 40

Therefore metal A is Sodium: Na and compound B is sodium hydroxide.

Therefore,

Therefore, compound B is sodium hydroxide

For C:

Sodium hydroxide reacts with aluminium oxide to give sodium aluminate Thus, C is sodium aluminate . The reaction involved is

Question 55:

Give the reaction involved during extraction of zinc from its ore by

  1. Roasting of zinc ore

  2. Calcination of zinc ore

Answer:

Extraction of zinc is shown in below figure:

Images show in extraction of zinc

Images Show in Extraction of Zinc

Images show in extraction of zinc

For (A):

The roasting is the process of burning of a ore in the presence of the excess air.

Therefore, the zinc sulphide will be heated with excess of the air.

The following reaction will be performed

For (B):

Whereas, the calcination is the process of heating of a ore in the absence of the oxygen,

Therefore, this will perform the following reaction.

Question 56:

A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.

Answer:

Metal m is copper which does not liberate when it reacts with acid as copper is least reactive than Hydrogen. Therefore, it cannot displace hydrogen from .

Copper reacts with oxygen to form copper (II) oxide, which is black in colour

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