Class-6 Dalal Introduction to Chemistry ICSE New Simplified

Class-6 Dalal Introduction to Chemistry ICSE New Simplified Solutions Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-1. We Provide Step by Step Solutions of Exercise/Lesson -1  Elements Compound and Mixtures with Objective Type Questions, Fill in the blanks and Give reason , Match the following of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-6.

Class-6 Dalal Introduction to Chemistry ICSE New Simplified Solutions Chapter-1


EXERCISE-1

Question 1.
State what is Science and give the basic bifurcation of Science with reasons.
Answer 1:
Branch of study  which includes the study of various experiments performed by a scientist with all observations recorded and inferences concluded is known as Science
 Science is bifurcated into three main category—

  1. Physics,
  2. Chemistry
  3. Biology

Question 2.
Give the basic difference between Inorganic Chemistry and Organic Chemistry.
Answer 2:

Including Metals Non-metals
Elements include Sulphur, Phosphorus, Sodium, Potassium
Gases include SO2, CO2, N
Acids include HCl, H2SO4, HNO3

Organic chemistry includes study of specific carbon compounds built up mainly of carbon and hydrogen.

Question 3.
State the functions of the following basic glass apparatus.

(a) Glass test tube
(b) Hard glass boiling tube
(c) Beaker
(d) Round bottom flask
(e) Retort

Answer 3:

(a) Glass test tube : test tube is used for heating chemicals and studying reactions in chemicals solution.
(b) Hard glass, boiling tube : Hard glass, boiling tube is resistant to chemicals and used for special purposes. It is made of pyrex.
(c) Beaker : Beaker is used for holding pouring and mixing solutions.
(d) Round bottom flask : round bottomed is used In preparation of gases, where heating is required. Since, heat is uniformly distributed throughout on heating.
(e) Retort : It is used for carrying out distillation experiments which include distillation of acids.

Question 4.
State why a round bottom flask is preferred to a flat bottom flask – during preparation of gases in the laboratory.
Answer 4:
It is preferred to flat bottom flask because in round bottom flask since heat is uniformly distributed in it

Question 5.
State the function of –

(a) The wooden handle at the end of the test tube holder.
(b) The asbestos fixed at the centre of the wire gauze.
(c) The clamp mounted on the rod of a retort stand.
(d) The air regulator in a Bunsen burner.
(e) The tap at the base of a burette.

Answer 5:

(a) being a poor conductor of heat The wooden handle at the end of test tube , makes holding the test tube holding easy.
(b) An asbestos fixed at the centre of the wire gauze initiates even distribution of heat to the bottom of the apparatus. It also prevents glass apparatus from cracking.
(c) for holding the apparatus and adjusting its level upwards or downwards.
(d)  It is used for regulating the flame as  air regulator has holes
(e)  helps in removing the measured liquid drop wise.

Question 6.        
State the method used for collecting the following gases –

(a) Oxygen – a gas slightly soluble in water.
(b) Ammonia – a gas highly soluble in water and lighter than air.
(c) Sulphur dioxide – a gas highly soluble in water and heavier than air.

Answer 6:

(a)  downward displacement of water.
(b) downward displacement of air.
(c)  upward displacement of air.

Question 7.
Explain in brief the importance of Chemistry in agriculture and production of various products.
Answer 7:

Importance of Chemistry

Fertilizers – A substance to improve fertility and supply of nutrients to plant and is essential for growth. EX- Ammonium nitrate – Urea – Phosphatic fertilizer – super phosphates.

Pesticides- Chemicals added to the soil, to kill pests. They include – Herbicides; insecticides; termiticides etc.

Food –  oils, butter, cheese,

Construction – Mortar, cement, glass,

Clothing –  silk Polyster nylon Rayon

Household –  liquefied petroleum gas or LPG, food preservatives, specific utensils and electronic goods

Daily usage – Paints, dyes, perfumes, paper, ink

Industrial –  alloys   machines and  automobiles,

Petrolium – Petrol, kerosene  diesel

Question 8.
‘Alchemists are older words for Chemists’. Discuss the statement in brief.
Answer 8:
Alchemists created substances through a seemingly magical process. Alchemy and alchemists are old terms used for chemistry and chemists. An alchemist named Nicolas Flamel claimed to transform metals into gold.

Question 9.
In the medieval ages – philosopher’s stone was connected with all transformations. Explain.
Answer 9:
During the medieval ages, in the 17th century, the so called philosopher’s stone held priority and the alchemists were successful to a certain extent that in the developmental process. It is said that later, it helped chemists to extract metals and develop a new approach in chemistry. Processes that involved modern chemistry started proving paths and chemistry regained its rightful position

Question 10.
State the contributions of

(a) Dimitri Mendeleev
(b) Antoine Lavoisier
(c) John Dalton – towards the development of Chemistry.

Answer 10:
(a) Dimitri Mendeleev :

  • Formulated the periodic table of elements
  • Mendeleev arranged the dozens of known elements by atomic weights and also predicted the properties of certain unknown elements.
  • He also discovered the periodic law.

(b) Antoine Lavoisier :

  1. In 1778 he recognised and named oxygen.
  2. In 1783 he recognised and named hydrogen.
  3. He wrote the first extensive list of elements and helped to reform chemical nomenclature.
  4. In 1774, he focused on the phenomenon of combustion. He conducted an experiment in which he heated pure mercury in a swan necked retort, leading to the discovery of oxygen.

(c) John Dalton :

  1. In 1803, he compiled his theory named as Dalton’s atomic theory.
  2. In his theory he discussed Matter that consists of particles called atoms which are invisible and cannot be created or destroyed. Later, this theory was contradicted in certain aspects by “Modern Atomic theory”

Question 11.
Differentiate between the terms – food preservatives and food processing with appropriate examples.
Answer 11:
Food preservatives – A Food preservatives (Benzoic acid Nitrates Sulphur compounds ) are chemicals that are added to food for following purpose

  1. Prevent decomposition by bacteria or microbes.
  2. Reduce risk of food  infections.
  3. Preserve nutritional quality of food.

Food processing :- Food processing is the transformation of agricultural products into food or one form of food into other forms

Question 12.               
Explain the term ‘cosmetics’ & ‘talc’. Name a few main ingredients in cosmetics the role they play.
Answer 12:

Cosmetics are mixtures of chemical compounds from natural sources or from synthetic sources. Cosmetics enhance or alter the appearance or fragrance of an individual.

Modified natural oils and fats, processed minerals like zinc oxide, iron and talc are a few examples of sources of compounds that are used in cosmetics.

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